(Christianity) The Tuesday before the onset of Lent.

plural of fat client

(computing) A complex client that does not rely on the server to do most of its processing.

plural of fat cat

A mass of fat stored in the rump of a beast as an adaption to heat and harsh environmental conditions or selection by man. / The relatively high probability of a relatively extreme outcome.

plural of fat tail

(statistics) Having a fat tail; leptokurtic.

(obsolete) malt vat, a vat that holds malt in a brewery.

A summer camp where obese children are sent to lose weight.

(idiomatic, vulgar, slang) To get an erection of the penis.