These words mean to make or become unclean, impure or stained with foreign matter. As implying the degree of uncleanness and its undesirability, soil is somewhat milder than dirty and refers largely to the inevitable staining with dust and grime, especially of clothing and linen, that occurs from ordinary use: to soil a towel by not thoroughly washing one’s dirty hands; a shirt collar soiled with sweat. In this context dirty is often substituted for soil , but dirty usually suggests creating an unclean condition that not only offends the aesthetic sense but may be injurious to health. Something that has been soiled , though dirty is now generally restricted to domestic uses: Don’t dirty the floor!; He will dirty the sofa if he puts his muddy shoes on it.

Smudge means to soil literally by begriming, as with soot, or by smearing, as with ink or dirty fingers. It often implies a degree of uncleanness as mild as, or milder than, that implied by soil , and suggests not making something dirty as much as it does spotting or staining it: Be careful not to smudge the drawing.

Dirty and soil are sometimes used figuratively in the moral context of character assassination: to soil a young girl’s spotless reputation; to dirty an honoured name.

Besmirch and sully , now found largely in literature of the past, have virtually lost all their earlier meanings of soiling , dirtying or smudging in a physical sense. Rather, besmirch is used as meaning to damage or dim the lustre of, as one’s honour or good repute: a reputation undeservedly besmirched by vicious gossip and slander. Sully is used in the same way, but carries a hint of greater injury and condemnation: his fame and standing as a diplomat sullied by the publicizing of his many romances.