Definition of frets:
(v) :
(transitive) To chafe or irritate; to worry.
(v) :
(transitive) To make rough, to agitate or disturb; to cause to ripple.
(v) :
(transitive) In the form fret out: to squander, to waste.
(v) :
(ambitransitive) To gnaw; to consume, to eat away.
(v) :
(ambitransitive) To be chafed or irritated; to be angry or vexed; to utter peevish expressions through irritation or worry.
(v) :
(intransitive) To be worn away; to chafe; to fray.