thatch / [unvoicedth]ach/ • n. a roof covering of straw, reeds, palm leaves, or a similar material. ∎  straw or a similar material used for such a covering. ∎ inf. the hair on a person's head, esp. if thick or unruly. ∎  a matted layer of dead stalks, moss, and other material in a lawn.• v. [tr.] cover (a roof or a building) with straw or a similar material: [as adj.] (thatched) thatched cottages DERIVATIVES: thatch·er n.

thatch. Thick roof-covering of reed, rushes, or straw, used in vernacular buildings, sometimes on medieval churches, and often on structures intended to fit within a Picturesque landscape, e.g. cottage orné.

Bibliography

N. Davey (1961);
West (1988)

thatch roof (a building), esp. with straw. XIV. repr. OE. þeċċan = OS. thekkian (Du. dekken), OHG. decchan (G. decken), ON. þekja :- Gmc. *þakjan, f. *þakam (OE. þæċ = MDu. dac, Du. dak, (O)HG. dach roof. ON. þak roof, thatch), f. *þak- :- IE. *tog- *teg- cover, repr. also by L. tegere.
Hence thatch sb. XIV.