OD /ˌoʊˈdiː/noun 10verb 1forms 8 noun10 •(of a pipe, tube, or shaft) Initialism of outer diameter or outside diameter. •(informal) Initialism of overdose. •Initialism of olive drab (“color of clothing, uniforms, tools, and equipment”).“He went to’ds de back, ma’am.” The negro opened the door and slid his legs, clad in army O.D. and a pair of linoleum putties, to the ground. “‘I’ll go git ’im.”’ — 1964 •Initialism of Doctor of Optometry. •Initialism of overdraft. •Initialism of organization development. •Abbreviation of Odisha: a state of India. •Initialism of overdrive. •Initialism of optical density. •(Australia) Initialism of over dimension, used on route numbers for large vehicles, and normally followed by a numeral, e.g. OD5. verb1 •(informal) Abbreviation of overdose (to take an overdose).She told me she'd love me and I told her I'd do the same / Then I OD'd in Denver and I just can't remember her name — 1979 formsOD'd · OD'ed · ODed · OD'ing · OD-ing · ODing · OD's · ODs