The noun baal fundamentally means owner or master — one who has authority over something or someone. In domestic usage it refers to a husband as the lord of the household. In wider usage it denotes one who possesses or controls (owner of land, of a skill, even 'dreamer' = baal chalomot). The word was also the name of the primary Canaanite storm-and-fertility deity, the storm god whom Israel constantly and catastrophically worshiped in place of YHWH.
The spiritual history of Israel is largely the history of choosing between YHWH and Baal. From the incident at Baal-Peor (Num 25) to Elijah's Mount Carmel confrontation (1 Kgs 18), the prophets thundered against Baal worship as the ultimate betrayal of the covenant. Hosea's profound insight (2:16) is that in the coming restoration, Israel will call God ishi (my husband) rather than baali (my lord) — a shift from slave-owner relationship to intimate marriage. Paul echoes this in Romans 11:4, citing the 7,000 who had not bowed to Baal, showing the remnant principle. The NT identifies the demonic 'Beelzebub' (lord of the flies) with baal, and Jesus' authority over demons is the final conquest that Elijah's contest only foreshadowed.