on the ropes
Against the ropes of a boxing ring and almost not able to stand up.
The fighter was on the ropes and could hardly lift his gloves.
Almost defeated; helpless; near failure.
The new supermarket took most of the business from Mr. Thomas's grocery, and the little store was soon on the ropes.
on the run
In a hurry; hurrying.
Jane called "Help!" and Tom came on the run.
Modern mothers are usually on the run.
Going away from a fight; in retreat; retreating.
The enemy soldiers were on the run.
on the safe side
Provided for against a possible emergency; well prepared.
"Please double-check these proofs, Mr. Brown," the printer said, "just to be on the safe side."
on the shelf
Laid aside; not useful anymore.
When a girl grows up, she puts childish habits on the shelf.
Mr. Myron's company put him on the shelf when he reached the age of 65.
on the side
In addition to a main thing, amount or quantity; extra.
He ordered a hamburger with onions and French fries on the side.
His job at the hospital did not pay much, so he found another on the side.
The cowboys in the rodeo competed for prize money and also made bets on the side.
Tending toward; rather.
Grandmother thought Jane's new skirt was on the short side.
on the sly
So that other people won't know; secretly.
The boys smoked on the sly.
Mary's mother did not approve of lipstick, but Mary used it on the sly.
on the spot
in a spot
upon the spot
At that exact time and at the same time or place; without waiting or leaving.
The news of important events is often broadcast on the spot over television.
When Tom ruined an expensive machine, his boss fired him on the spot.
In trouble, difficulty, or embarrassment.
Mr. Jones is on the spot because he cannot pay back the money he borrowed.
Bill is on the spot; he invited George to visit him, but Bill's parents said no.
In danger of murder; named or listed for death.
After he talked to the police, the gangsters put him on the spot.
on the spur of the moment
On a sudden wish or decision; suddenly; without thought or preparation.
John had not planned to take the trip; he just left on the spur of the moment.
Mary saw a help-wanted advertisement and applied for the job on the spur of the moment.