'pectoralis' originates from Latin, specifically the word 'pectorālis', where 'pectus' meant 'breast, chest'.

'pectoralis' passed from Classical Latin 'pectorālis' into Medieval/Neo-Latin anatomical usage and was borrowed into English scientific vocabulary (as 'pectoralis') in modern anatomical terminology.

Initially, it meant 'of the chest' (descriptive); over time it has also come to be used as the name of specific chest muscles in anatomy ('the pectoralis').