What does "freeze up" mean?

To be adversely affected by ice, and not function.

What is a synonym for "freeze up"?

Common synonyms include: block, breakdown, clam up, congeal, crash, crystallize.

verb

verb ·Uncommon ·Advanced level

Verb

1
To be adversely affected by ice, and not function.
"But these precautions lost some of their merit when the L.T. trains themselves became frozen up at depots overnight."
2
(of machines and software) To come or bring to a sudden halt, stop working (functioning). ambitransitive
"Since the last update, the program freezes up after a few minutes of use."
3
(of people and other animals) To stop or be stopped due to attentiveness, fear, surprise, etc. ambitransitive
"Despite all of the rehearsals, as soon as I got on stage I froze up."
4
To become cold and formal in demeanour. intransitive

"But these precautions lost some of their merit when the L.T. trains themselves became frozen up at depots overnight."