This generally means “massive.” Obviously, it comes from the root of Cyclops, the monster from Greek and Roman mythology. “Cyclops” means “round eye” which was used to describe a giant creature with one eye.
The word seems to be common masonry industry, to refer to stonework done with large stones. The Cyclops of legend were supposedly masons of a sort – having built massive walls out of stones.
From Wordnik (which cites The Century Dictionary from the 1800s).
applied to an early style of masonry, sometimes imitated in later ages, constructed of stones either unhewn or more or less irregularly shaped and fitted together, usually polygonal, but in some more recent examples approaching regular horizontal courses, and often presenting joints of very perfect workmanship