'outpatient-acquired' is a modern compound formed from 'outpatient' + 'acquired'. 'outpatient' itself is formed from the prefix 'out-' + 'patient' (from Latin 'patiens', from 'patior' meaning 'to suffer'). 'acquire' originates from Latin 'acquirere', where 'ad-' meant 'to/toward' and 'quaerere' meant 'to seek or obtain'.

'acquire' changed from Latin 'acquirere' to Old French (e.g. 'acquerre') and then into Middle/Modern English as 'acquire'; 'outpatient' is a Modern English formation combining 'out-' + 'patient', and 'outpatient-acquired' is a 20th-century medical compound describing conditions obtained in outpatient care.

Initially 'acquire' meant 'to get, obtain'; the compound 'outpatient-acquired' has specifically come to mean 'obtained/contracted in an outpatient setting' (most commonly referring to infections), a specialized medical usage.