In insects (especially ants, wasps, and bees), the enlarged hind section of the body that contains the abdomen and reproductive organs.
From Greek 'gaster' (belly, stomach). First applied to insects in entomological terminology because this body section is visibly larger and distinct, resembling an enlarged stomach or belly.
Ants can actually spray formic acid from their gasters as a weapon, and if you watch nature documentaries, entomologists will use this technical term—but it comes straight from the Greek word for 'belly,' making insect anatomy a time capsule of ancient Greek.
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