Synonyms for Decompress (same or very similar meaning)
WordNet sense 1 (restore to its uncompressed form):
uncompressWordNet sense 2 (decrease the pressure of):
depressurize, depressuriseWordNet sense 3 (become less tense, rest, or take one's ease):
relax, unbend, unwind, loosen upFrom the ODE community, based on WordNetadd/edit