O`
prep. Of, on (esp. In phrases: o`clock; will-o`-the-wisp). [abbreviation] -o suffix forming usually. Slang or colloq. Variants or derivatives (beano; wino). [perhaps from *oh] -o- suffix terminal vowel of combination. Forms (neuro-; franco-). [originally greek] usage this suffix is often elided before a vowel, as in neuralgia.