'salt-avoiding' is a modern English compound formed from the noun 'salt' and the present-participle form of the verb 'avoid'. 'salt' originates from Old English 'sealt' (from Proto-Germanic '*saltą'), where the root referred to the substance 'salt'; 'avoid' originates from Old French (e.g. 'esvuiter'/'eviter') ultimately from Vulgar Latin related to Latin 'vitare' meaning 'to shun'.

'salt-avoiding' developed by straightforward compounding in modern English from existing words: Middle English/Old English 'salt' and Middle English forms of 'avoid' (from Old French), resulting in the adjectival compound used in contemporary English.

Initially the elements separately meant 'salt' and 'to avoid'; over time they combined without change in the basic senses to create the compound adjective meaning 'tending to avoid salt' (either as a dietary preference or ecological trait).