Wordnet 3.0
NOUN (1)
1.
unscrupulously accusing people of disloyalty (as by saying they were Communists);
The Collaborative International Dictionary of English v.0.48:
McCarthyism \McCarthyism\ prop. n. [from Senator Joseph
McCarthy, who repeatedly asserted without evidence that
numerous communists were present in the United States
government.]
Unscrupulously accusing people of disloyalty (as by saying
they were Communists).
[WordNet 1.5 +PJC]
WordNet (r) 3.0 (2006):
McCarthyism
n 1: unscrupulously accusing people of disloyalty (as by saying
they were Communists)