stand up is a verb meaning "rise to one's feet". It carries 7 recorded senses.
rise to one's feet
“The audience got up and applauded”
refuse to back down; remain solid under criticism or attack
be standing; be upright
“We had to stand for the entire performance!”
resist or withstand wear, criticism, etc.
“Her shoes won't hold up”
“This theory won't hold water”
Definitions, synonyms and semantic relations for stand up come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.