An accent in excess of an “O” is known as an “accent mark” or “diacritic” and may alter the pronunciation of the letter “O” in a few languages.All O&M c/o D/O I/O o/b o/d I/O, at input/output See all meanings Idioms and phrases c/o, at treatment of idiomwill be the past participle form, most effective suited to excellent tenses. Bec