noun: Obsolete spelling of oath [A solemn pledge or promise that invokes a deity, a ruler, or another entity (not necessarily present) to attest the truth of a statement or sincerity of one's desire to fulfill a contract or promise.]
adjective: Initialism of over the horizon: a form of radar that can detect targets at very long ranges, typically hundreds to thousands of kilometres, beyond the radar horizon.
noun: (politics) Abbreviation of other. [An other, another (person, etc), more often rendered as another.]
noun: (advertising) Initialism of opportunity to hear.