'cartoony' originates from English, specifically the word 'cartoon' combined with the adjectival suffix '-y', where 'cartoon' came from Italian 'cartone' (see below).

'cartoon' entered English in the mid-18th century from Italian 'cartone' meaning 'large paper' or 'cardboard'; earlier it is related to Medieval Latin 'charta' meaning 'paper'. The English adjective 'cartoony' is a later formation using '-y' to mean 'characterized by'.

Initially, 'cartoon' referred to a full-size preparatory drawing on paper or cardboard; over time it shifted to mean a humorous or satirical illustration, and 'cartoony' came to mean 'resembling or characteristic of cartoons'—i.e., stylized, exaggerated, or comical.