means a pause partway through a performance, film, or event, giving the audience a chance to stretch, refresh, or step out before the next part begins

from From Latin intermissio, 'a leaving off, an interval,' built from inter- 'between' and mittere 'to send or let go' — so quite literally a 'sending between,' a gap dropped into the middle of things. The same mittere fuels a whole family of English words, from 'mission' to 'permit,' all sharing that sense of letting something go forth.