Alternative form of triple O

Initialism of olefin and surfactant.

Abbreviation of month(s) old.

Abbreviation of year(s) old; also yo, y.o. / (knitting) Abbreviation of yarnover.

(medicine) Initialism of rule out: used to indicate that a certain possible diagnosis should be considered, and appropriate tests performed to rule it out.

Alternative form of lameo

Alternative form of lameo

Alternative form of will-o'-the-wisp

Alternative spelling of righto

(insurance) Abbreviation of directors and officers.