pack has 25 distinct synonyms spread across 11 of its 22 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its one recorded opposite is unpack.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
fill to capacity
“This singer always packs the concert halls”
carry, as on one's back
“Pack your tents to the top of the mountain”
set up a committee or legislative body with one's own supporters so as to influence the outcome
“pack a jury”
treat the body or any part of it by wrapping it, as with blankets or sheets, and applying compresses to it, or stuffing it to provide cover, containment, or therapy, or to absorb blood
“The nurse packed gauze in the wound”
a complete collection of similar things
Synonyms, antonyms and the broader and narrower relations for pack come from Princeton University’s WordNet. Full sources and licences.
a convenient package or parcel (as of cigarettes or film)
an association of criminals
“police tried to break up the gang”
an exclusive circle of people with a common purpose
a group of hunting animals
a sheet or blanket (either dry or wet) to wrap around the body for its therapeutic effect
a bundle (especially one carried on the back)