What is the meaning of Tierce?

A third.

Synonym of terce: the third canonical hour or its service.

A cask of a certain size, or its volume used as a measure of capacity. Larger than a barrel but smaller than a hogshead.

The third tone of the scale. See mediant.

A sequence of three playing cards of the same suit. Tierce of ace, king and queen is called tierce-major.

The third defensive position, with the sword hand held at waist height, and the tip of the sword at head height.

An ordinary that covers the left or right third of the field of a shield or flag.

One sixtieth of a second, i.e., the third in a series of fractional parts in a sexagesimal number system. (Also known as a third.)

feminine singular of tiers

third

terce

Alternative form of tiers

Source: wiktionary.org