wild-goose chase 
(wīldgs)
(wīldgs)n.
A futile or protracted pursuit or search.
- triphthong
- triphthongal
- tripinnate
- tripinnately
- triplane
- triple
- triple agent
- triple alpha process
- triple bond
- Triple Crown
- triple-decker
- triple-digit
- triple digits
- triple-double
- triple figure
- triple-header
- tripleheader
- triple jump
- triple measure
- triple play
- triple point
- triple rhyme
- triple sec
- triplet
- tripletail