definition of
semi

[1] #1 semi n. [semifinal] one of the two competitions in the next to the last round of an elimination tournament. wn

[2] #2 semi n. [trailer truck, tractor trailer, trucking rig, rig, articulated lorry] a truck consisting of a tractor and trailer together. wn

[3] #3 semi n. [semitrailer] a trailer having wheels only in the rear; the front is supported by the towing vehicle. wn