Tipping

Noun

 * 1) The practice of leaving a tip (gratuity).
 * 2) The dumping of rubbish.

Verb
tipping

Thesaurus
aslant, aslope, atilt, bevel, beveled, bias, biased, canting, careening, inclinational, inclinatory, inclined, inclining, leaning, listing, out of plumb, out of square, pitched, raking, recumbent, shelving, shelvy, sideling, sidelong, slant, slanted, slanting, slantways, slantwise, sloped, sloping, tilted, tilting, tipped, tipsy