The term 'WHIRLYBIRD WHIRLER' is a combination of two words, 'WHIRLYBIRD' and 'WHIRLER'. The term 'WHIRLYBIRD' is a slang term for a helicopter, which is an aircraft that uses rotors to generate lift and thrust. The term 'WHIRLER' refers to someone who operates the helicopter, usually a pilot. Therefore, the term 'WHIRLYBIRD WHIRLER' is used to describe a person who operates a helicopter. The crossword solution for this term is 'ROTOR', which is the part of the helicopter that generates lift and thrust.