From WordNet (r) 3.0 (2006):
pa
n 1: an informal term for a father; probably derived from baby
talk [syn: dad, dada, daddy, pa, papa, pappa,
pop]
2: a short-lived radioactive metallic element formed from
uranium and disintegrating into actinium and then into lead
[syn: protactinium, protoactinium, Pa, atomic number
91]
3: a unit of pressure equal to one newton per square meter [syn:
pascal, Pa]
4: a Mid-Atlantic state; one of the original 13 colonies [syn:
Pennsylvania, Keystone State, PA]
5: an electronic amplification system used as a communication
system in public areas [syn: public address system, P.A.
system, PA system, P.A., PA]