A honeycomb was a structure made of hexagonal cells created by bees to live and produce honey in.
In 2269, Spock compared the windows of an unknown ship to a honeycomb, citing their hexagonal shape. (TAS: "Beyond the Farthest Star")
In 2369, Geordi La Forge compared subspace with "…a huge honeycomb with an infinite number of cells". (TNG: "Schisms")
In an alternate 2374, Tom Paris said the transverse bulkheads on the RMS Titanic were like a honeycomb. (VOY: "Year of Hell")
Honeycomb was mentioned in the final draft script of TOS: "The Corbomite Maneuver" (dated 3 May 1966), as that script referred to the Fesarius as being "in the shape of a round [...] honeycomb." This allusion was written out of the teleplay by the time a second revised final draft of the script (dated 20 May 1966) was issued.