'astomia' originates from Greek, specifically from the root 'stóma' (Greek 'στόμα'), where 'stóma' meant 'mouth' and the prefix 'a-' meant 'without'.

'astomia' is a modern medical formation created from Ancient Greek elements 'a-' + 'stóma'; it was adopted into medical/Latinized usage and then into specialized English medical literature to denote absence of a mouth.

Initially it meant 'without a mouth' in the literal root sense, and over time this sense has persisted in medical usage to refer specifically to congenital absence or severe underdevelopment of the oral opening.