What does "gridiron" mean?

Gridiron: (Naut.) An openwork frame on which vessels are placed for examination, cleaning, and repairs.

Additional senses

  1. 2.(Sport) A football field. Gridiron pendulum. See under Pendulum. -- Gridiron valve (Steam Engine), a slide valve with several parallel perforations corresponding to openings in the seat on which the valve moves.

Sources