Crossword puzzle
From Memory Alpha, the free Star Trek reference
A crossword puzzle is a puzzle in which words have to be inserted in a grid by following clues.
In 2152, a crewmember of the Enterprise did a crossword puzzle while the crew was forced to retreat into the ship's catwalk. Captain Archer helped her to solve one of few open questions, naming the first Vulcan ambassador to Earth with six letters ending in R. Archer gave her the correct answer, Solkar. (ENT: "The Catwalk")
