bad top

bad top

[′bad ‚täp]
(mining engineering)
A weak roof in a coal mine; sometimes develops following a blast.
References in periodicals archive ?
It has what is referred to as "bad top" and has been plagued by roof falls in the past.
And not a bad top 10 that prove teenagers are not as empty-headed as people think.
Controversy is the word of the year as Miley Cyrus's twerking, NSA spying, zombies, selfies and Breaking Bad top Yahoo's most searched terms in 2013.
That's not a bad top four, and that doesn't even include Chara and Marc Savard, who are decent aces in the hole.
4: Which word appears in top 10 hits by Britney Spears, Soup and Bad Top?