IPA: /ˈwɪslər/
KK: /ˈhwɪslər/
A person or thing that makes a whistling sound, or a type of animal known for its whistling call.
The whistler in the park attracted many listeners with its beautiful tunes.
Whistler → The word 'whistler' is formed from 'whistle' (from Old English 'hwistlian', meaning to make a sound by forcing air through pursed lips) and the suffix '-er' (meaning a person who). A whistler is a person who makes a whistling sound.
Think of someone who 'makes a sound' ('whistle') and the '-er' just means a person. A whistler is someone who creates that sound.