'3-C-branched' is a modern English compound formed from the numeral '3', the chemical symbol 'C' (for 'carbon', from Latin 'carbo' meaning 'coal'), and 'branched' (the past participle/adjectival form of 'branch').

'branch' comes into English via Old French 'branche' and Middle English 'branche', developing into modern English 'branch' and its adjective/past participle 'branched'. The convention of using numerals with 'C' to indicate specific carbon positions (e.g., '3-C-') is a 20th-century chemical nomenclature practice, producing terms like '3-C-branched'.

Originally 'branch' denoted a bough or limb; over time it extended to mean a division or offshoot and then the verb/participial sense 'to form branches'. In chemical usage it evolved into a positional descriptor indicating substitution at a specific carbon, now meaning 'having a substituent at carbon-3'.