regent bowerbird (Sericulus chrysocephalus)

plural of regent-bird

The region of Brazil comprising the states of Goiás, Mato Grosso, Mato Grosso do Sul and the Distrito Federal.

plural of register plate

In rope-making, a disc having holes arranged so as to give the yarns passing through them their proper position for entering into the general twist.

plural of registry office

(informal) Synonym of register office (“office for registering births, marriages and deaths”)

(historical) A Victorian love token, a ring set with precious stones whose initial letters spelled regard (e.g. ruby, emerald, garnet, amethyst, ruby, diamond) or some other word of affection.

plural of regard ring

(set theory) One of the axioms in axiomatic set theory, equivalent to the statement that every non-empty set contains a member that is disjoint from that set.