endure, persevere

我慢(がまん　する)	Persevere! Never give up! Endure it! Be patient! $$$

忍耐(にんたい)	Patience, forbearance -basically it is a more formal version of 我慢. However, 我慢 can be used in the active sense of “keep doing what you’re doing, keep rolling that rock up the hill, don’t quit.” Whereas, 忍耐 has more a passive nuance – “Continue doing nothing, fight the urge to counter-attack or snap back.”

根気(こんき)	Patience. You need 根気 to be able to 我慢。 Often used like 根気がいい（she’s very patient!) or, 根気よくxxxした！(you did xxx very patiently!)

忍ぶ(しのぶ)	A very old word – from feudal times – and not used anymore. It means “to endure or bear,” but is usually used only in the context of bearing shame or disgrace. The ninja connection of this kanji lies in the SECOND meaning, which is restricted to this one idiom: 人目を忍ぶ（ひとめをしのぶ）, meaning, to do secretly, or to do without being seen. OLD

堪忍する(かんにんする)	Not useful.