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1. Cause to become unblocked
   - unstuff
    
2. Become less tense, less formal, or less restrained, and assume a friendlier manner
   - relax
    
3. Make one's body limber or suppler by stretching, as if to prepare for strenuous physical activity
   - limber up, warm up
    
4. Become less tense, rest, or take one's ease
   - relax, unbend, unwind, decompress, slow down
    
5. Cause to feel relaxed
   - relax, unstrain, unlax, unwind, make relaxed

Derived forms: loosened up, loosens up, loosening up

Type of: act, affect, behave, change state, disengage, do, exercise, free, turn, work out