1. to put or use in place of another
2. (Now Rare) to take the place of
3. Chem. to replace as a substituent
1. To exchange - interchange, change, replace; see exchange 1.
2. To take the place of
act for, do the work of, replace, supplant, displace, supercede, take another's place, double for, answer for, make way for, count for, serve in one's stead, pass for, go for, go as, step up, fill another's position, take over another's duties, fill in for, pinch-hit for*, take the rap for*, sub for*, spell*, go to bat for*, ring in*, front for*, fill someone's shoes*.

Ex.: For better health, substitute yoghurt for the sour cream. (i.e., use yoghurt)