noun, noun which may take the genitive case particle 'no'
by one's side; within arm's reach
Refers to a place close to where one sits or stays; often used in set phrases like 座右の銘 (a favorite motto kept nearby).
彼は座右に辞書を置いて勉強している。
He studies with a dictionary at his side.
この言葉を座右の銘としている。
I keep these words as my personal motto.
noun
honorific indirect reference to addressee
Used in formal letters to refer to the recipient indirectly, or written beside the addressee's name to show respect. Archaic in modern correspondence.
古い手紙では、宛名の横に「座右」と添えて敬意を表した。
In old letters, '座右' was written beside the addressee's name to show respect.
側 is a more general word for 'nearby' or 'beside', while 座右 specifically implies a place close to where one sits, often with a nuance of something kept handy.
From 座 (seat) + 右 (right), originally referring to the right-hand side of one's seat, a convenient place to keep important items. The exact historical derivation is uncertain.