Gaster (γαστήρ) means womb, belly, or stomach. It appears about 9 times in the New Testament. Most uses are literal: the womb of a mother (Matthew 1:18 — 'before they came together, she was found with child in her womb'), or the belly. One significant use is in Titus 1:12 where Cretans are accused of being 'lazy gluttons' (gasteres argai — 'idle bellies').
The theological significance of gaster peaks in the Incarnation texts. Matthew 1:18 and Luke 2:21 both use it for Mary's womb — the holy vessel of the Son of God. The same word used for animal appetite and human gluttons is used for the womb that bore the Savior. God chose a belly to be His first home among us. This is the scandal and wonder of the Incarnation: the infinite became intimate, the eternal entered a womb. Titus 1:12's 'idle bellies' contrast with the productive, purposeful servant life of gospel ministry — one who lives for stomach versus one who lives for the kingdom.