'Ig-domain-like' originates from multiple sources: 'Ig' is an abbreviation of 'immunoglobulin' (from New Latin 'immunoglobulin'), 'domain' originates from Old French 'domaine' (from Latin 'dominium'), and the suffix '-like' comes from Old English 'līc' where it meant 'similar'.

'domain' changed from Old French 'domaine' (and Latin 'dominium') and eventually became modern English 'domain'; the adjective-forming element '-like' comes from Old English 'līc' and developed into the modern suffix '-like'; 'Ig' is a 20th-century scientific abbreviation of 'immunoglobulin', and the compound 'Ig-domain-like' arose in molecular biology to denote similarity to an Ig domain.

Initially, the components meant 'immunoglobulin' (a class of antibodies), 'domain' (an area or discrete structural unit), and 'like' (similar); over time the compound has come to mean specifically 'having structural similarity to an immunoglobulin domain' in protein-science contexts.