1.  touch on(v = verb.communication) - refer to or discuss briefly;
is one way to advert, bring up, cite, mention, name, refer
Sample sentences: Somebody ----s something; Something ----s something

2.  touch on(v = verb.stative) bear on, come to, concern, have-to doe with, pertain, refer, relate, touch - be relevant to; "There were lots of questions referring to her talk"; "My remark pertained to your earlier comments"
Sample sentences: Something ----s somebody; Something ----s something

3.  touch on(v = verb.change) bushel, doctor, fix, furbish up, mend, repair, restore - restore by replacing a part or putting together what is torn or broken; "She repaired her TV set"; "Repair my shoes please"
is one way to ameliorate, amend, better, improve, meliorate
Sample sentences: Somebody ----s something

4.  touch on(v = verb.change) affect, bear on, bear upon, impact, touch - have an effect upon; "Will the new rules affect me?"
is one way to alter, change, modify
Sample sentences: Somebody ----s something; Somebody ----s somebody; Something ----s somebody; Something ----s something

   To mention briefly, or in passing. [PJC]

VB  mean, signify, express, import, purport, convey, imply, breathe, indicate, bespeak, bear a sense, tell of, speak of, touch on, point to, allude to, drive at, involve, declare, understand by.

common touch, finishing touch, get in touch, get in touch with, keep in touch, light touch, midas touch, not touch, out of touch, sense of touch, soft touch, touch, touch a chord, touch and go, touch base, touch bottom, touch down, touch football, touch modality, touch off, touch perception, touch screen, touch sensation, touch system, touch typing, touch up, touch up paint, touch upon