Abarim Publications' online Biblical Greek Dictionary
αγκος
The noun αγκος (ankos) means curve or bend, and is in the classics specifically used to describe the hollow of a mountain glen. It comes from the same Proto-Indo-European root as the words ankle, angle, anchor and apparently also the name Ankara (perhaps after a bend in the river Cubuk). It's not used in the New Testament but from it (or from the same Proto-Hellenic root "ankos", meaning curve or bend) come the following terms.
Note how all the following words have to do with "bending" natural reality after some purpose or design. This in turn suggests that Ankara was named so because it, like many other cities in Anatolia and the Levant, was a famous wisdom center, where people studied science and technology:
- The noun αγκαλη (agkale), a bent arm (or a bent knee). In the classics, this word appears mostly in plural and mostly to describe an embracing or enfolding. It could even describe engulfing air or the embrace of the horrors of deep waters. In the New Testament, it occurs in Luke 2:28 only. Note that from the Hebrew word for knee, namely ברך (berek), comes the verb ברך (barak), meaning to bless.
- The noun αγκιστρον (agkistron), meaning a hook and specifically a fish-hook (Matthew 17:27 only). Note that the sole reference to fishing with a hook in the Old Testament speaks of catching Leviathan (Job 41:1). The word for fish-hook used here is חכה (hakka), from the root חנך (hanak), which deals with the beginning of discernment. From this same root comes the name Hanukkah, of the Feast of Dedication.
- The noun αγκυρα (agkura) meaning anchor. This word is used 4 times in the New Testament, see full concordance, the latter of which (Hebrews 6:19) speaks of the anchor of ελπις (elpis), hope, which is not about wishful thinking but about applying a familiar procedure to a new situation: so that even though the situation is new, the outcome is certain.
αναγκη
The noun αναγκη (anagke) means necessity in the sense of a natural need, fate, or some inescapable course of logic (if B is true only when A is true, then A is a necessity of B). But it may also mean compulsion, or a force applied by a superior (bigger, stronger) to an inferior (smaller, weaker). The latter sense allowed our word to also describe torture in the classics, which demonstrates that our word does not so much speak about the internal sensibilities of the person who has a must need, but rather about the external conditions that force the person in some disagreeable position or situation.
Our word αναγκη (anagke) speaks of force and subdual, about enslavement and restriction. Its opposite is completeness (שלום, shalom), autonomy (χριστος, christos) and freedom (ελευθερια, eleutheria), and an action performed out of necessity (not having enough) is the opposite of an action performed out of generosity (having a surplus).
It's not clear where our word comes from, but its formation or adoption into Greek may have been helped along by its similarity to a combination of the common preposition ανα (ana), meaning on, upon or again-and-again, plus αγκος (agkos), a bend of hollow (the noun αγκαλη, afkale means bent arm; see above).
Our noun is used 18 times in the New Testament, see full concordance, and from it derive:
- The verb αναγκαζω (anagkazo), meaning to force or compel. This verb is used 9 times; see full concordance.
- The adjective αναγκαιος (anagkaios), meaning compelling, constraining or pertaining to applied force (bereft of proper adjectival equivalents in English, exasperated translators have been noted to resort to adverbs like perforce or necessarily). Like the parent noun, this adjective may describe a logical necessity (Acts 13:46), but may also refer to compliance (malleability, bendability), and thus trustworthiness of soldiers of even willfully controllable body parts (1 Corinthians 12:22). Our word may refer to the necessities of life, and thus mean indispensable, and even the forceful ties of blood relations: kin or the kind of friends everybody needs as a basic requirement of life (Acts 10:24). This versatile adjective is used 8 times; see full concordance.
- The adverb αναγκαστως (anagkastos), meaning of necessity or forcibly (1 Peter 5:2 only).
- Together with the preposition επι (epi), also meaning on or upon: the substantively used adverb επαναγκες (epanagkes), necessary [things] or rather restrictive or constrictive [impositions] (Acts 15:28 only). Paul's concerns here appear to contradict his assertion that "it is for freedom that Christ has set you free" (Galatians 5:1), but the freedom in Christ is a governed or lawful freedom; a freedom that is guaranteed by imposed limitations (or "limitations" that don't limit but rather guarantee freedom).