grummet vs holdfast

grummet and holdfast both are nouns.

Word	Noun	Adjective	Verb	Adverb
grummet	Yes	No	No	No
holdfast	Yes	No	No	No

As nouns, holdfast is a hypernym of grummet; that is, holdfast is a word with a broader meaning than grummet:

grummet: fastener consisting of a metal ring for lining a small hole to permit the attachment of cords or lines
holdfast: restraint that attaches to something or holds something in place

Other hypernyms of grummet include fastener, fastening, fixing.

grummet (noun)	holdfast (noun)
fastener consisting of a metal ring for lining a small hole to permit the attachment of cords or lines	restraint that attaches to something or holds something in place