A knot that is usually used as a hitch.
It consists of
two half-hitches created mirror-image around a post.
It can also result when you tie a reef or
square knot correctly, but then tighten one rope much
more than the other; the tight rope ends up acting as
the "post", and the loose rope takes on the larks-head
configuration.
An ASCII art version:
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\_________________/
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