A general online dictionary defines "idiom" as "A speech form or an expression of a given language that is peculiar to itself grammatically or cannot be understood from the individual meanings of its elements."
In English, for example, "raining cats and dogs" for heavy rain, "break a leg" meaning "to wish someone good luck".
Here goes your million question (or actually a ten thousand question, I don't know) on the American TV game "Who Wants to Be a Millionaire":
What is your answer to the question above?
Needs a lifeline? 50:50, Phone-a-Friend, Ask the Expert, or Ask the Audience? Whatever is your choice, here it is:
Glossed as: train gone sorry, or more literally, train zoom sorry
English translation: The train has been just gone, sorry.
I don't wish to repeat what I just said.
Are you confused? Yeah, just a pun. :D
If a signer is about to finish the last sentence with a listener at around the same time another friend joins this group's conversation. The person might be curious and ask, "What did you just say?" The signer or listener in the group might say "train gone sorry." It means that they wouldn't repeat what they just talked. Usually, it is a friendly remark or sometimes a joke.
Back to TRAIN GONE, SORRY" idiom (see video below contributed by June Ann LeFors).
"Sorry, I cannot repeat what I've just said." Or, "Sorry, you've just missed it and I won't repeat it."
But, the signer who missed the train can zinger "the train is back!"
The signer then would sign "CIGARETTE-BURNED-OUT". See the video (contributed by June Ann LeFors, 2017) for a demonstration.
You cannot get the burned-out cigarette back!
Another common ASL idiom is the verb phrase FINISH+TOUCH in which means "been there" or "been to" in English.
STAND-ON-FENCE for "uncertain", MIND+DISAPPEAR for "mind slips", FUNNY+ZERO for "That's not funny!" (in a semi-humorous sense), WON'T BITE-YOU for "don't be afraid of me".
The ASL sign "BIRD+PICKHEAD" in the video (contributed by LeFors, 2017) above means "my thought just disappeared" or "I just forgot now."
More: FREE EYES (allowed to watch), FISH SWALLOWED (guillible), MONEY BEHIND, THINK+EASY, DRY DISCUSSION (no further discussion or discussion closed), RIGHT++ MIND-HEARING (No wonder, it's a hearing thing), RESPECT BLOW-AIR-HAND (completely no respect).
In American Sign Language (ASL), there are some idioms of its own and some idioms influenced by a spoken language (English). Both languages may share a few similar idioms.
For example, the idiom BROWNNOSE (try to please the other; to suck up) in ASL, for example, is one of the terms that English and ASL share the same.
BROWNNOSE: to seek favor or approval from (someone) by obsequious behavior for personal gain.
Video above: one ASL sign with different facial expressions can convey many different meanings: speechless, foot in mouth, flustered, 'cat get your tongue', etc.
Anything else you know? Email me.