Wordnet 3.0
NOUN (1)
1.
rotor consisting of large rotating airfoils on a single-rotor helicopter that produce the lift to support the helicopter in the air;
The Collaborative International Dictionary of English v.0.48:
main rotor \main rotor\ n. (Aviation)
The assembly of large rotating airfoils (blades) on a
helicopter that produce the lift to support the helicopter in
the air.
[WordNet 1.5]
WordNet (r) 3.0 (2006):
main rotor
n 1: rotor consisting of large rotating airfoils on a single-
rotor helicopter that produce the lift to support the
helicopter in the air