From The Collaborative International Dictionary of English v.0.48 :
Kat \Kat\ (k[aum]t), n. (Bot.)
An Arabian shrub ({Catha edulis) the leaves of which are
used as tea by the Arabs.
[1913 Webster]
From WordNet (r) 3.0 (2006) :
kat
n 1: the leaves of the shrub Catha edulis which are chewed like
tobacco or used to make tea; has the effect of a euphoric
stimulant; "in Yemen kat is used daily by 85% of adults"
[syn: kat, khat, qat, quat, cat, Arabian tea,
African tea]