deeply absorbed in thought; "as distant and bemused as a professor listening to the prattling of his freshman class"; "lost in thought"; "a preoccupied frown"
a constitutional tendency to be gloomy and depressed
characterized by or causing or expressing sadness; "growing more melancholy every hour"; "her melancholic smile"; "we acquainted him with the melancholy truth"
a measuring instrument that sends out an acoustic pulse in water and measures distances in terms of the time for the echo of the pulse to return; "sonar is an acronym for sound navigation ranging"; "asdic is an acronym for antisubmarine detection investigation committee"