loosen · verb I or T /ˈluː.sən/
loosen
C2 to become loose or make something loose
Dictionary example:
He loosened his tie.
Learner example:
Do we not want our children to be as happy as possible? By loosening their ropes, we enable them to choose the way most suitable for themselves. (Certificate of Proficiency in English; C2; Spanish)
loosen up
C2 to become more relaxed with other people
Dictionary example:
After a while he loosened up.
Learner example:
What is sure is that one needs to find something that will make him loosen up. (Certificate of Proficiency in English; C2; Greek)
