This is the 7329th most frequent Chinese word.
脫衣
"脱衣" means "to take off clothes."
In this sentence, '脫衣' means the act of removing clothing, describing a habitual action.
他在睡觉前总是习惯性地脫衣。
He habitually takes off his clothes before sleeping.
Here, '脫衣' describes the necessity to remove clothing for a specific purpose or reason.
为了检查伤口，他不得不脫衣展示背部。
To check the wound, he had to take off his clothes and show his back.
The term '脫衣' in this case refers to people removing outer clothing as a preparation for a forthcoming activity—in this scenario, swimming.