What is meant by the term precipitate?

a precipitate usually refers to an insoluble compound created in situ (in solution). It is called a precipitate because much like rain, it will combine and crash (descend toward the bottom of the beaker, if it is more dense) out of solution, due to its insolubility. this occurs after the start of the chemical precipitation reaction. look up the reaction of lead nitrate with sodium iodide, Pb(NO3)2 + NaI ---> PbI + NaNO3 (not balanced). The lead nitrate undergoes replacement to become insoluble lead iodide, which will precipitate out as a bright yellow solid.