v. 25B6; verb
he couldn't understand anything we said : COMPREHEND, grasp, take in, see, apprehend, follow, make sense of, fathom; unravel, decipher, interpret; informal work out, figure out, make head or tail of, get one's head around, take on board, get the drift of, catch on to, get; Brit. informal twig, suss (out).
she understood how hard he'd worked : APPRECIATE, recognize, realize, acknowledge, know, be aware of, be conscious of; informal be wise to; formal be cognizant of.
I understand that you wish to go : BELIEVE, gather, take it, hear (tell), notice, see, learn; conclude, infer, assume, surmise, fancy.