The son of Ruth and Boaz, father of Jesse and grandfather of David, grandson of Naomi. / A male given name from Hebrew of biblical origin.

(Internet, informal, humorous) Obligatory; prepended to the name of a topic being mentioned to avoid accusations of being off-topic.

(non-productive) Against; facing; a combining prefix found in verbs of Latin origin. / (botany) Of a reversed shape.

(category theory) The set of objects of a category.

A river in Russia; the westernmost of the three great Siberian rivers.

Abbreviation of obstetric. / (golf) Initialism of out of bounds. / Abbreviation of obligatory. (as in "ob. link" on Usenet) (see ObLink at c2.com; see also ob-) / Abbreviation of Old Babylonian.

(sports) Initialism of Olympic best. / (television, radio) Initialism of outside broadcast. / Initialism of old boy. (male graduate; also a CB radio operator's term of address for a male)

Initialism of overcome / overtaken by events (i.e., now obsolete)

Initialism of Officer of the Order of the British Empire. / Initialism of operating-basis earthquake. / Initialism of out-of-body experience. / Initialism of outcome-based education.

Initialism of Office of Bilingual Education. / (US politics, historical) Initialism of Office of Business Economics, now BEA. / Initialism of Oregon Board of Education.