The name Anak in the Bible
Anak and his descendants the Anakim are a tall and numerous people, reckoned among the Nephilim (Numbers 13:33) and the Rephaim (Deuteronomy 2:10). The name of the father of Anak is Arba (Joshua 21:11), and his city, Hebron, is given to Caleb (Joshua 15:13). Caleb subsequently drives out the three sons of Anak (perhaps again three subdivisions of the Anakim), whose names are Sheshai, Ahiman and Talmai (Joshua 15:14).
Etymology of the name Anak
The name Anak is generally spelled as ענק and only once, in Joshua 22:11, as ענוק. The added letter waw serves as a vowel and doesn't alter the meaning of the name.
The name Anak comes from the assumed Hebrew root ענק ('nq):
NOBSE Study Bible Name List, Jones' Dictionary of Old Testament Proper Names and BDB Theological Dictionary all agree: the name Anak means Long-Necked, but even though these Anakim were certainly tall, there is no indication that they specifically had long necks (the regular word for neck is צואר (sawwa'r). Judging from its usage in Scriptures, the name Anak is probably meant to mean Jewelry, or possibly more specific: Necklace
And where the name Anakim in English looks like an ordinary ethnonym, in Hebrew it's spelled ענקים, which is a plural form, not a ethnonym. The Anakim were possibly called ענקים (=Necklaces) because they wore ornaments around their necks. This name may also allude to their wealth.