spring-rail frog

noun

: a frog having a movable wing rail held against the point rail by springs and normally presenting an unbroken running surface to wheels using the main track but operating also to permit the passage of trailing wheels from a diverging track

Love words?

You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Start your free trial today and get unlimited access to America's largest dictionary, with:

• More than 250,000 words that aren't in our free dictionary
• Expanded definitions, etymologies, and usage notes
• Advanced search features
• Ad free!