retrench vs trim back

retrench and trim back both are verbs.

Word	Noun	Adjective	Verb	Adverb
retrench	No	No	Yes	No
trim back	No	No	Yes	No

As verbs, trim back is a hypernym of retrench; that is, trim back is a word with a broader meaning than retrench:

Other hypernyms of retrench include bring down, cut, cut back, cut down, reduce, trim, trim down.

retrench (verb)	trim back (verb)
make a reduction, as in one's workforce	cut down on; make a reduction in
tighten one's belt; use resources carefully