'second-from-last' is a modern English compound formed from 'second' + 'from' + 'last'. 'second' ultimately comes from Latin, specifically 'secundus' meaning 'following'; 'from' comes from Old English 'from' (from Proto-Germanic *fram) meaning 'away, forth'; and 'last' comes from Old English 'lǣst' meaning 'the latest, final'.

'second' passed into Middle English via Old French 'seconde' from Latin 'secundus'; 'from' remained in English from Old English 'from'; 'last' developed from Old English 'lǣst' into Middle English and then modern English. The compound 'second-from-last' is a later, transparent compound formed in modern English to mean 'the one immediately before the last'.

Each element largely kept its original sense ('secundus' = following; 'from' = away/from; 'last' = final), and together the compound came to mean 'immediately before the last' (penultimate) in modern usage.