Abarim Publications' online Biblical Hebrew Dictionary
The verbs זכך (zakak) and זכה (zaka) are obviously related in form and have the same meaning, namely that of being without contamination, that is: being wholly according to purpose. It's highly significant that the Hebrew sense of sinlessness was metaphorized by the transparency of oil and glass, in stead of, for instance, the hotness of fire or the strength of some fierce animal, or even some heavenly tranquility or limitless omnipotence.
The verb זכך (zakak) means to be pure or clean. It occurs less the half a dozen times in the Bible (Job 9:30, 15:15, 25:5, Lamentations 4:7). Its derivations are:
- The adjective זך (zak), meaning pure or clean. This word is used to describe olive oil that is free from foreign substances (Exodus 27:20, Leviticus 24:2) or frankincense of that same quality (Exodus 30:34, Leviticus 24:7). The same word may describe a man (Job 8:6), a man's ways (Proverbs 16:2), conduct (Proverbs 20:11), philosophy (Job 11:4) or prayer (Job 16:17).
- The feminine noun זכוכית (zekokit), meaning glass. This noun occurs only once, in Job 28:17, where Job prizes it next to gold but both as less valuable than wisdom (see our article on the name Hochma).
The verb זכה (zaka) means to be clear, clean or pure in much the same way as the previous verb (Job 15:14, Psalm 51:6, Isaiah 1:16). This verb occurs slightly more often than זכך (zakak) and has no derivatives.