1) to put (something) back in its place; to take the place of (a person, thing); to supply, use, (a person, thing) as a substitute (replace)

2) to take the place of a person who is ill, absent etc (stand-in)

3) to take the place of (an earlier thing) (supersede)

4) to take the place of (a person, machine, system etc) (supplant)

5) a person learning to, able to, take the place of another (especially an actor) (understudy)