I. phrasal
1.
a. : to remain loyal or faithful to : support , defend
stand by the Constitution
stood by her husband through all his troubles
a strong minority would always stand by the king — G.G.Coulton
b. : to stick to
stood by all his promises
: maintain
2. : to get ready or in position to operate
stand by the lifeboats
II. intransitive verb
Etymology: Middle English standen by, from standen to stand + by
1.
a. : to be near at hand : be present
made the statement with several witnesses standing by
b. : to remain apart or aloof
how can you stand by and let your son ruin himself
2.
a. : to be or to get ready to act
standing by to await instructions
ordered to stand by to let go the anchor
b. of a transmitting station : to be ready to send signals
c. of a receiving station : to remain tuned in