Abarim Publications' online Biblical Greek Dictionary
The verb διδασκω (didasko) means to teach (hence the English words didactic and autodidact). To creative minds our verb may vaguely remind of the verb διδωμι (didomi), meaning to give, or the verb δεω (deo), meaning to bind (and whose passive perfect form is δεδεμαι, dedemai; that which has been bound), but formally it stems from the unused verb δαω (dao), meaning to learn. This verb ultimately derives from the Proto-Indo-European root dens-, meaning to learn/teach. An obviously related root dent- means tooth (hence words like dentist and trident), and the association between teeth and learning is clearly ancient. The Hebrew verb שנן (shanan) means to sharpen (of the mind, to teach; Deuteronomy 6:7) and its derived noun שן (shen) means tooth, and since at least the age of Aristotle, wisdom teeth have been known as wisdom teeth.
It appears that the ancients understood that learning isn't about copy-pasting data from one brain to the other but rather a continued chomping off and chewing of the same experiences. A personality, moreover, is also not constituted by the food one absorbs, it's just maintained by it and brought to bloom. It appears that the ancients knew what our modern schools systems don't, which is that a proper diet can make the difference between a healthy squirrel and a sick one, but no amount of food can turn a squirrel into a horse. Likewise, even though every child can be fed the same mental nutrition that the tribe hunts and gathers, every child can only grow into what it has always been. When children have matured enough to switch from milk to solid food (1 Corinthians 3:2), lion cubs will naturally switch to meat (arguments, debates and disputes that "hunt, kill and absorb" other minds) whereas rabbit kits will naturally turn to plants (arts, music, sodality; non-competitive harvests of naturally replenishing bounties). The greater, world-wide human culture, of course, needs to consist of all kinds of minds and works really quite like the biosphere and its vast interlocked economy of bio-energy. For more on this, read our article on the world-mind of the human mental-sphere.
Our verb occurs 97 times in the New Testament, see full concordance, mostly with Jesus as subject. Ultimately, Jesus is the Word of God in the flesh (John 1:14), and anything that can be known about anything that actually exists is contained by him (Colossians 2:3). All else is religious nonsense and tooth-decaying make-believe (Matthew 15:9, 23:15, Deuteronomy 18:20-22).
It should be noted that the wisdom tradition in Israel and Judea was as strong and versatile as the entertainment industry is in ours. Teaching and learning sat at the heart of society, and sound knowledge was recognized as the source of prosperity and peace, not to mention marvel and delight. Another Hebrew verb that means to sharpen is חדה (hada), which also (or more so) means to rejoice. The noun חידה (hidda) literally means "sharpie" and is the word for riddle.
Medieval Christianity may have managed to turn the words of the Bible into a religion of ignorance and compliance, it originated in a culture of astonishingly advanced scientific knowledge and artistic skills. The ancients entertained each other by posing riddles (Exodus 7:11, Judges 14:12, 1 Kings 10:1, Ezekiel 17:2, John 18:38), in order to playfully test each other's intellectual prowess (John 3:10) and to ever grow into more effective stewardship and ultimately freedom (Galatians 5:1, John 8:32). The deity they worshipped came to them through his Word (Genesis 15:1), who could be known by studying and discussing creation (1 Kings 4:33-34, Romans 1:20, 1 Corinthians 11:13-14, and of course the whole of Psalm 19).
From our verb derive:
- The adjective διδακτικος (didaktikos), which appears to be a Pauline invention meaning "teachy" or "having the didactic knack." It's used only twice in the New Testament (1 Timothy 3:2 and 2 Timothy 2:24 — despite their grave topics, the letters to Timothy are full of jest and banter and clearly written out of great fondness) and appears to describe having an aptitude or zeal for teaching. People who routinely face packs of blood-curdling pupils know that it takes vast and superhuman talents to persuade young minds to not overeat on the mental candy offered on Facebook and its likes, but on occasion down a hearty scoop of bone-growing treasure. This aptitude appears to begin with a genuine concern for the people taught, and strives to settle on the fleeting point of balance between disarming charm and rigid authority. Doing so, teachers save generations (which is why in enlightened societies teachers enjoy the highest respect and the biggest salaries — in really advanced cultures, teachers pay no tax either).
- The adjective διδακτος (didaktos), meaning taught. In the classics this word may describe things that are taught (lessons, wisdoms), or collectively: teachable things (as opposed to experiences or notions that can't be traded in such ways). It may also describe people who are taught and, hopefully, are now learned. In the New Testament this word occurs only twice, in John 6:45 and 1 Corinthians 2:13, both times arguing that all things that are actually true are true because they either pertain to or were created by the Creator. Ultimately, since the source of all things that are actually real is the Creator, all things that can be learned can only be learned from the Creator. Also see the adjective θεοδιδακτος (theodidaktos), below.
- The noun διδασκαλια (didaskalia), meaning a teaching. As its English counterpart, this Greek noun may either refer to the act of teaching (Romans 12:7), a thing taught (Colossians 2:22), or the method of teaching used (Ephesians 4:14). On occasion our word is used somewhat reflexively, which result in a preferred English translation of "learning" (Romans 15:4). Our word is used 21 times in the New Testament, see full concordance, but a close synonym is the noun διδαχη (didache; see below).
- The noun διδασκαλος (didaskalos), meaning teacher. This word technically refers to one person teaching, but in colloquial terms ("going to the teacher") it also became synonymous with "school." This word is one of the most common epithets of Jesus in the New Testament; it occurs 58 times, see full concordance, and from it come:
- Together with the pronoun ετερος (heteros), meaning another: the verb ετεροδιδασκαλεω (heterodidaskaleo), meaning "to teach something else" (1 Timothy 1:3 and 6:3 only). Over the centuries, the gospel of Jesus Christ has been mistaken for a gleaming chain of doctrines, and anybody who offered alternative interpretations of the going standard was hit over the head with this dangerous verb. The secret, of course, is that the gospel of Jesus Christ ensures liberty of pursuit and diversity of thought, and anybody (whether pope, priest or parent) who restricts, chokes, chops off or declares off-limits is guilty of this evil of "teaching something else."
- Together with the adjective καλος (kalos), meaning good (or rather: godly): the adjective καλοδιδασκαλος (kalodidaskalos), meaning good-teacherly (Titus 2:3 only). This word appears to be another Pauline invention, which makes play of the pleasing yet coincidental similarity between the word didaskalos and the adjective kalos. Our English word "school" comes from the Greek word σχολη (schole), meaning rest. It describes being free from having to labor like a normal person, and thus having freedom to read books and visit with interesting teachers. Consequently, school was far from mandatory in the first century, and a teacher could only stay in business if he could attract affluent customers (Luke 8:3). Particularly in societies that valued practical skills and abhorred speculative philosophies, peddlers of sugary nonsense would quickly be found out (Proverbs 12:11, 28:19) and the only way to be recognized as a good-teacher was to be up to snuff with the latest intel and offer it in a fun-filled, exciting and engaging manner. Being good-teacherly is precisely that: to conduct your business in such a way that the benefits are obvious and difficulties are exciting, and that ultimately the provisions keep rolling in without having to beg or nag for them.
- Together with the noun νομος (nomos), meaning (natural) law: the noun νομοδιδασκαλος (nomodidaskalos), meaning teacher of the law, someone who delivers the wisdom mined by researcher to the common folk to execute (Luke 5:17, Acts 5:34 and 1 Timothy 1:7 only).
- Together with the adjective ψευδης (pseudes), meaning false: the noun ψευδοδιδασκαλος (pseudodidaskalos), meaning false teacher (2 Peter 2:1 only).
- The noun διδαχη (didache) meaning a teaching. It differs only slightly, and mostly technically, from the noun διδασκαλια (didaskalia; see above), and although both words may describe both the act of teaching and the lesson taught, our noun διδαχη (didache) mostly describes the latter. Our English word "doctrine" comes from the Latin docere, to show and teach (hence our word "doctor," which means "teacher" or "demonstrator") and ultimately from the Latin decere, to be fitting or seemly (hence our word "decent"). Quite unfortunately, our word "doctrine" has become attached to otherwise unsubstantiated beliefs (hence "indoctrination") and most systems of belief are more concerned with social "decency" and conformity than with demonstrable and verifiable validity. All that means that our word διδαχη (didache) is better not translated with "doctrine." A "teaching" both covers the material taught and the method with which is taught, and is most suited to reflect the compass of our Greek noun. It occurs 30 times; see full concordance.
- Together with the amazing noun θεος (theos), meaning God: the adjective θεοδιδακτος (theodidaktos), meaning "taught by God." This word occurs only once, in 1 Thessalonians 4:9, but its idea also occurs in John 6:45, 14:26, 1 Corinthians 2:13 and 1 John 2:27. This word meaning "God-taught" reflects what Paul writes in Romans 1:20: "Since the creation of the world his invisible attributes, his eternal power and divine nature, have been clearly seen, being understood through what has been made." It urges people who hunger for wisdom to open their eyes and study creation rather than the latest fad in philosophy or lifestyle. Or in the word of the prophet Isaiah: "And all your sons will be taught of YHWH and great will be the peace of your sons" (Isaiah 53:4).
A fun non-Biblical word is the adjective διδακτυλιαιος (didaktuliaios), meaning of two fingers [long or wide]. It has nothing to do with our word group but comes from δυο (duo), meaning two, and δακτυλος (daktulos), meaning finger (hence our word didactyl, which describes any two-fingered creature, like the ostrich). Still, even though this adjective has formally nothing to do with our word group, it's very possibly that the words for learning and teaching sounded to a Greek ear like having to do with being double- or rather quick-fingered (somewhat in the way modern Cockney rhyming slang works). It's furthermore possible that the author of Mark had precisely this colloquial association in mind when he wrote about Jesus dealing with the deaf stutterer by sticking his fingers into the man's ears (Mark 7:33, see Isaiah 6:9).