'Strange' is Latin for 'external, foreign' — from 'extraneus.' Oddity was originally just outsiderness.
Unusual or surprising; difficult to understand; not previously visited, seen, or encountered; unfamiliar.
From Old French 'estrange' (foreign, alien, curious), from Latin 'extrāneus' meaning 'external, from without, foreign,' derived from 'extrā' (outside). The Latin root is from PIE *h₁eǵʰs (out). The original meaning in English was 'from another country, foreign' — a stranger was literally an outsider. The shift from 'foreign' to 'peculiar, odd' happened gradually through the 14th and 15th centuries, as what is foreign came to be perceived as what is unfamiliar and therefore puzzling. Key
'Strange' and 'extraneous' are doublets — both descend from the same Latin word 'extrāneus,' but 'strange' arrived through Old French (losing its Latin shape) while 'extraneous' was borrowed directly from Latin centuries later. The physicist's term 'strange quark' was named by Murray Gell-Mann in 1964 because the particles decayed in unexpectedly slow, 'strange' ways.