unicellular- having only one cell

 

unicorn- a horse-like animal that has one horn growing our of the middle of its forehead

 

unicycle- a one-wheeled vehicle on which the rider sits and pedals

 

unidirectional- moving in only one direction

 

unify- to join together into one group

 

unilateral- one sided

 

unique- one of a kind; unusual or rare

 

unison- an instance of saying the same words or sounds at the same time; a group that sound like one

 

unit- one group

 

unitard- a one-piece leotard and tights combination