noun

1. a brown or black, tarlike, bituminous substance that consists mainly of hydrocarbons, found in large flat beds or made by refining petroleum
2. a mixture of this with sand or gravel, for cementing, paving, roofing, etc.

Etymology: ML asphaltus < Gr asphaltos, prob. < a-, not + sphallein, to cause to fall, injure (< IE base *(s)p(h)el-, to split off > spill): ? so named because of use as protective substance for walls

transitive verb