Deposit, precipitate, sediment, dregs, lees, grounds mean matter which settles to the bottom of or is let fall from suspension in a fluid (as air or water).
Deposit, the most comprehensive term, refers to matter let fall by a natural or mechanical process to remain where it settles until there is a visible layer or accumulation.
Precipitate denotes a usually solid substance separated from a solution or suspension by some chemical interaction or by some physical force (as heat, cold, or centrifugal force).
Sediment applies to matter that settles to the bottom of a liquid. The word may be used of other matters with emphasis on a foreign element that disturbs the clarity or purity of something.
Dregs and lees typically apply to the sediment found at the bottom of a cask or a bottle of some alcoholic or fermenting liquor, but the terms may be used of other things that, like a sediment, suggest that something now fair has been formerly turbid, foul, or offensive, or that imply the worthlessness of what lies at the bottom or is left over.
Grounds is used of the small particles left after serving or drinking a beverage (as coffee); usually the term carries no implication of a disagreeable sediment but simply of one from which all the flavor has been exhausted.