Anak: the forebear the Bible attaches to the unusually tall clans who held Hebron, named as the measure of an enemy Israel thought unbeatable
Anak is less a word with a meaning than a name with a reputation. It belongs to one stretch of the story, Israel's approach to Canaan, and it appears almost entirely inside one fixed phrase: the sons, or the children, of Anak. These are the people the scouts met at Hebron, and the report that came back was about size and walls, not about anything the name itself says.
Hebrew usually puts "the" in front of the name, which makes it read less like one man's name and more like a label for a kind of people, roughly "the Giant." Two verses do treat Anak as a person in his own right, naming Arba as his father when they explain Hebron's older name. Everywhere else the word answers the question "what sort of people are these?" rather than "who was their grandfather?"
Later readers folded the name into a much larger story. Numbers 13:33 sets the sons of Anak beside the Nephilim (נְפִלִים), and Deuteronomy counts them among the Rephaim (רְפָאִים), so the Bible's various oversized peoples ended up gathered into one category of ancient giants. When the text needs a plural for the group itself it uses a separate word, the Anakites (עֲנָקִי).
Where the name came from is genuinely unknown. It is spelled exactly like the Hebrew word for a necklace (עֲנָק), and older commentators guessed that these were the long-necked people, or the ones who wore neck-chains. But the stories only ever call them tall, never long-necked, and Hebrew has a different everyday word for a neck. Two of the three sons named at Hebron, Sheshai and Talmai, do not look like Hebrew names at all, which points to the name belonging to Canaan's older population rather than to Israel's own language.
Nuances
Disputed
Whether עֲנָק in these texts ever denotes an individual eponymous ancestor, or functions throughout as a class term for the tall Hebron population.
- contestedThe word is fundamentally a group designation. The article in most occurrences reads as a title (roughly "the Giant"), the ancestor to whom Hebron's older name is attached is Arba rather than Anak, and the individual "Anak" of Joshua 15:13 and 21:11 is a secondary back-formation from the group name.; BDB, s.v. עֲנָק ("later (erroneously) as eponymous ancestor of Anakim"); E. C. B. MacLaurin, "Anak/Ἄναξ," Vetus Testamentum 15, fasc. 4 (1965): 468-474
- contestedThe genealogical notices are taken at face value: Anak is a named forefather, son of Arba, whose three sons hold Hebron, and the plural Anakim are his descendants.; HALOT, s.v. עֲנָק; Jeffrey H. Tigay, Deuteronomy, JPS Torah Commentary (Philadelphia: Jewish Publication Society, 1996), on Deut 1:28; 9:2