Abarim Publications' online Biblical Greek Dictionary
αχος
The noun αχος (achos) means pain or distress (hence our word "ache"). It stems from the same Proto-Indo-European root "heg-", meaning to be upset or afraid, as the English verb to ail. It occurs frequently in Homer, and always as a state of mind. Apart from two derived names, this word does not occur in the New Testament, but note the accidental similarity with the noun αχυρον (achuron), chaff or grinding residue.
αχθος
The noun αχθος (achthos) means burden or load (literally, of camels and such) or grief or sorrow. It is thought to stem from a poorly attested PIE root "hedg-", to squeeze or oppress, but it's obviously similar to the previous, as native speakers of Greek would have surely noticed. This noun does not occur independently in the Bible, but from it comes:
- Together with the adverb αγαν (agan), very much (an otherwise unused variant of μεγας, megas, great or large): the verb αγανακτεω (aganakteo), meaning to be greatly irritated or vexed. It's actually not certain whether this verb comes from αχθος (achthos), burden, and may very well also have something to do with the adjective ακτεοσ (akteos), to-be-drawn or to-be-lead, from the verb αγω (ago), meaning to lead. But whatever its pedigree, this verb is used 7 times, see full concordance, and from it in turn comes:
- The noun αγανακτησις (aganaktesis), meaning great irritation, vexation or indignation (2 Corinthians 7:11 only).
- The verb οχθιζω (ochthizo), meaning to be very angered, vexed or irritated. This verb does not occur in the New Testament but from it comes:
- Together with the prefix προς (pros), which describes a motion toward: the verb προσοχθιζω (prosochthizo), meaning to be very angry or irritated with or toward someone (Hebrews 3:10 and 3:17 only).
αλγος
The noun αλγος (algos) refers to physical or mental pain or distress, or the cause of it. How this word differs from αχος (achos) isn't clear. It's also not clear where our word comes from, but there is also a verb αλεγω (alego), which means to care and which derives from the PIE root "hleg-", to care. Another word that comes to mind is λοιγος (loigos), ruin, which is unused in the New Testament, but is related to the noun λοιμος (loimos), plague or pestilence. This in turn brings to mind the familiar noun λογος (logos), whose Hebrew equivalent, namely דבר (dabar), is closely related to the noun דבר (deber), meaning pestilence.
All this suggests that there might be some Semitic thought behind this noun, but there's not much in Hebrew or Aramaic that resembles it. In Pesachim 2.7, the Sages are quoted to declare that during Pesah, a person is not permitted to chew wheat and place the masticated wad as dressing on his wound because the saliva would leaven the wheat, and that's not permitted. The verb for this particular kind of chewing, so as to produce a medicinal paste, is לעס (la'as). Patients may have been known by this same verb, and an evolution from la'as to lagas to algos seems not impossible. But of course this is no more than an entertaining guess.
From our noun αλγος (algos) comes the verb αλγω (algeo), to feel pain (physically or mentally). Neither this noun nor the verb are used independently in the New Testament, but from the verb derives:
- Together with the preposition απο (apo), meaning from or out of: the verb απαλγεω (apalgeo), meaning to be beyond feeling pain, for whatever reason: to be numb from overexposure, to be relieved somehow, to choose rationality over anything felt, good or bad. From this word derives our English noun "analgesic". It occurs in the New Testament in Ephesians 4:19 only.