Depress, weigh, oppress mean to put such pressure or such a load upon a thing or person as to cause it or him to sink under the weight.
Depress implies a lowering of something by the exertion of pressure or by an overburdening; it most commonly implies a lowering of spirits by physical or mental causes. It may suggest lowering of bodily vigor or the power of certain organs to function (as by a drug, a disease, or an external condition).
In reference to other things (as market prices or social or cultural states) depress often suggests a lowering in activity, intensity, or vigor.
Weigh in this relation is used with down, on, or upon and carries a weaker implication of the result or lowering than depress but a stronger implication of the difficulty or burdens imposed upon a person or thing.
Like weigh, oppress stresses the burden which is borne or is imposed and, like depress, the consequent ill effects (as the lowering of spirits or of power to function) or in its more common sense (see WRONG), a trampling down, a harassing, or a subjection to heavy penalties.