threesome (no sexual meaning); a set of three upon horses

a Russian sleigh or carriage pulled by a team of three horses running abreast

a modern Russian triumvirate

The Troika is an amusement park ride, designed and manufactured by HUSS Maschinenfabrik in the early 1980's. The ride is available in both transportable and permanent forms, although due to the total weight and size of the ride (35 tons, plus an additional 27 tons for the temporary base and platform), transportable Troikas are unpopular and uncommon.

the cardinal number that is the sum of one and one and one