Real Dictionary

thrum
verb: When something such as a machine or engine thrums, it makes a low beating sound.

thrum in American English 1
the row of warp thread ends left on a loom when the web is cut off
to provide with or make of thrums; fringe
intransitive verb: to play on a stringed instrument, as a guitar, by plucking the strings, esp. in an idle, monotonous, or unskillful manner; strum
noun: an act or sound of thrumming; dull, monotonous sound
transitive verb: to play (a stringed instrument, or a melody on it) by plucking the strings, esp. in an idle, monotonous, or unskillful manner; strum

thrum in American English 2
a thrumming or the sound of this
to strum (a guitar, banjo, etc.)
to thrum a guitar, etc.
noun: one of the ends of the warp threads in a loom, left unwoven and remaining attached to the loom when the web is cut off
transitive verb: to insert short pieces of rope yarn through (canvas) and thus give it a rough surface, as for wrapping about a part to prevent chafing

thrum in British English 1
noun: a repetitive strumming or recitation
verb: to strum rhythmically but without expression on (a musical instrument)

thrum in British English 2
noun: any of the unwoven ends of warp thread remaining on the loom when the web has been removed
verb: to trim with thrums