1. briefly discuss or mention something
touch on an issue
When you 'touch on something' you briefly deal with something in a written or spoken discussion without going into too much detail. You will often hear this used in professional or academic environments. In social situations, it can be a good expression to use when asking to deal with sensitive matters. "Would you mind if we touched on your issues with your mother?" To 'touch on' something can also mean to come near to being. "She was touching on rude when she made that statement."