'travel-size' originates from Modern English as a compound of the words 'travel' and 'size'. 'travel' originates from Old French 'travail'/'travailler' (ultimately from Latin 'trepalium'), where the root referred to 'work' or 'toil' and later to a 'journey'; 'size' originates from Old French 'sis'/'sise' (from Latin 'situs' and related forms), meaning 'position' or 'measurement'.

'travel' developed in Middle English from Old French 'travail' (originally meaning work or toil) and shifted semantically toward journey or movement; 'size' came via Old French 'sise' into Middle English to mean extent or measurement. In Modern English the two words were combined into the compound 'travel-size' to denote a size appropriate for travel, often first seen in the 20th century with the rise of packaged consumer goods.

Individually the components referred to 'journey' (travel) and 'measurement/extent' (size). Over time the compound 'travel-size' acquired the specific commercial sense 'small size intended for travel' and is now used both adjectivally and nominally.