'animoseness' originates from English, specifically formed from the word 'animosity' and the suffix '-ness', with the ultimate root traceable to Latin 'animus' meaning 'mind, spirit'.

'animoseness' is a later English formation modeled on nouns ending in '-ness' and influenced by the established noun 'animosity' (from Old French/Latin); 'animosity' came into English via Old French 'animosité' from Latin 'animositas' (from 'animosus').

Initially the root 'animus' meant 'mind, spirit, courage' in Latin; over time derivatives such as 'animosity' and the later-formed 'animoseness' narrowed to mean 'hostile feeling' or 'ill will'.