1) Road hazard 2) Urban lid 
A manhole cover is a removable plate forming the lid over the opening of a manhole, to prevent anyone or anything from falling in, and to keep out unauthorized persons and material. Manhole covers date back at least to the era of ancient Rome, which had sewer grates made from stone. Manhole covers are often made out of cast iron, concrete or a com...
Manhole cover is London Cockney rhyming slang for brother.
[n] - a flush iron cover for a manhole (as in a street)
noun a flush iron cover for a manhole (as in a street)