'nonisogenic' originates from Modern English, specifically formed by the prefix 'non-' + 'isogenic', where 'non-' meant 'not' and 'isogenic' meant 'having the same genetic origin'.

'isogenic' ultimately derives from Greek elements 'iso-' (equal) + 'genic' (from 'genos', kind/origin), adopted into scientific English to mean 'of the same genetic origin'; 'non-' was later attached in English to negate it, producing 'nonisogenic'.

Initially a straightforward negation meaning 'not isogenic'; the term has retained that core meaning and is used mainly in technical genetic and experimental contexts to denote different genetic backgrounds.