noun, noun which may take the genitive case particle 'no'
usual state of things; ordinary course; way things normally are
A noun and の-adjectival use for what is normal, usual, or the expected course of things. Often appears in set phrases such as 世の常, meaning 'the way of the world.'
人の心が変わるのは世の常だ。
It is the way of the world for people's feelings to change.
これを常のこととして受け止めてはいけない。
You must not accept this as the normal state of affairs.