In early use often hardly more emphatic than the mod. dirty; it is now a violent expression of disgust, seldom employed in polite colloquial speech. [OED]
Related: Filthily; filthiness.
1590s, from French squalide and directly from Latin squalidus "rough, coated with dirt, filthy," related to squales "filth," squalus "filthy," squalare "be covered with a rough, stiff layer, be coated with dirt, be filthy," of uncertain origin. Related: Squalidly; squalidness; squalidity.
1620s, "state or condition of being miserable and dirty," from Latin squalor "roughness, dirtiness, filthiness," from squalere "be filthy" (see squalid).
"filthy beggar, leper," c. 1300, from Medieval Latin lazarus "leper," from Lazarus (q.v.), the name of the beggar in the biblical parable. Sometimes also lazard, with pejorative suffix.
late 14c., "dung, excrement, feces; filth, dirt," from Old French ordure "filth, uncleanliness" (12c.), from ord, ort "filthy, dirty, foul," from Latin horridus "dreadful" (see horrid). Related: Ordurous.
1540s, from Latin squamosus "covered with scales, scaly," from squama "scale," perhaps related to squalus "foul, filthy" (see squalid). Middle English had squame "a scale" (late 14c.), from Old French esquame, from Latin squama. Alternative form squamose attested from 1660s.