trimmer vs joist

trimmer and joist both are nouns.

Word	Noun	Adjective	Verb	Adverb
trimmer	Yes	No	No	No
joist	Yes	No	No	No

As nouns, joist is a hypernym of trimmer; that is, joist is a word with a broader meaning than trimmer:

trimmer: joist that receives the end of a header in floor or roof framing in order to leave an opening for a staircase or chimney etc.
joist: beam used to support floors or roofs

trimmer (noun)	joist (noun)
joist that receives the end of a header in floor or roof framing in order to leave an opening for a staircase or chimney etc.	beam used to support floors or roofs
capacitor having variable capacitance; used for making fine adjustments
a machine that trims timber
a worker who thins out and trims trees and shrubs