The term 'lazy-eyed' is formed from the adjective 'lazy' and the noun 'eye,' with the suffix '-ed' indicating a characteristic. 'Lazy' comes from Middle Low German 'lasich,' meaning 'idle.'

'Lazy' entered English in the 16th century, and the compound 'lazy-eyed' appeared in the 19th century to describe someone with an eye that does not focus properly.

Initially, 'lazy-eyed' simply described the appearance of an eye that seemed inactive or unfocused, but it became associated with specific medical conditions over time.