Main Entry : 1roof
Pronunciation : 'rüf, 'ruf
Function : noun
Inflected Form(s): plural roofs /'rüfs, 'rufs also 'rüvz, 'ruvz/
Etymology : Middle English, from Old English hrOf;
akin to Old Norse hrOf roof of a boathouse and perhaps to Old Church Slavonic stropu roof
1 a (1) : the cover of a building
(2) : material used for a roof : ROOFING
b : the roof of a dwelling conventionally designating the home itself
<didn't have a roof over my head>
<they share the same roof>
2 a : the highest point : SUMMIT
b : an upper limit : CEILING
3 a : the vaulted upper boundary of the mouth
b : a covering structure of any of various parts of the body <roof of the skull>
4 : something suggesting a roof: as
a : a canopy of leaves and branches
b : the top over the passenger section of a vehicle

Merriam-Webster Online Dictionary

<Edited by Tim Luo for better viewing.>