Ahab was a 9th-century king of Israel (real, also attested outside of the Bible) and his name, אַחְאָב ʔaḥʔāb, is often claimed to mean 'uncle' on the grounds that it's literally אַח־אָב 'brother of father'. It actually isn't אַח־אָב, though—the construct state of אָח ʔāḥ 'brother' is historically and commonly אֲחִי ʔăḥî (the original root is *ʔḫw and III-w nouns are complicated), and while אַח ʔaḥ is attested it's a late analogical creation that never really took hold. What אַחְאָב ʔaḥʔāb actually is is a noun phrase 'a brother is father' (Hebrew doesn't have a copula, or indeed any kind of verb, in the present tense), and the reason the first a is short—that is, tonic lengthening didn't happen—is just because names are univerbations with a single accent, like construct chains but not, in this case, a construct chain.
It's actually a kind of theophoric name, i.e. a name comprising two elements, one of which is the name of a god and the other usually a verb but also often a noun. Theophoric names are popular in every Semitic language and they usually explicitly name the god: Hebrew יֹונָתָן yônātān 'YHWH has given, Jonathan', Punic ḤNBʕL 'Baal is favourable, Hannibal', Arabic عَبْدُ ٱللّٰه ʕabdu llāh 'servant of Allah, Abdullah' (← this one is a construct chain), Akkadian é-a-na-ṣi-ir /Ea-nāṣir/ 'Ea protects, Ea-nasir'.
There is a significant class of, I guess, semi-theophoric names (they're usually still called theophoric) in which the god is instead referred to obliquely by some generic title, though. Baal was actually one of these initially, just meaning 'lord'—that's why Saul's son was called אֶשְׁבַּעַל ʔešbaʕal 'man of baʕal', certainly referring to YHWH, before it became too closely associated with specifically Baal Hadad and he was retconned to אִישׁ־בֹּשֶׁת ʔîš-bōšet 'man of shame'. Certainly by the second half of the first millennium BCE, unqualified Baal basically always referred to Baal Hadad in the Levant and the broader Phoenician sphere of influence (the Akkadian version, bēlu(m)/Bel, was Marduk).
Anyway, often the god is conceived to be part of the family and the title is a kinship term, usually 'father' (e.g. אֲבִימֶלֶךְ ʔăbîmelek 'father is king') or 'brother' (e.g. אֲחִימֶלֶךְ ʔăḥîmelek 'brother is king'). That's what's going on with Ahab's name, 'brother is father': the god, YHWH (regardless of the story, we can be pretty sure about that—both of his sons and his daughter or sister all have Yahwistic theophoric names: אֲחַזְיָהוּ ʔăḥazyāhû 'YHWH has grasped, Ahaziah', יְהוֹרָם yəhôrām 'YHWH is high, Jehoram', עֲתַלְיָהוּ ʕătalyāhû 'YHWH is pre-eminent, Athaliah'), is seen as the father of the family, and he is like a brother to the child.
Or the other way around.
But Ahab does not mean 'uncle'.
