是非

1. Origins, structure, and basic meaning

• Structure: 是非 (ぜひ) means “by all means” as an adverb and “right or wrong” as a noun.
• Basic usage: It can strengthen an invitation or introduce a discussion of whether a plan is right or acceptable.
  • 近くへ来たら是非この店に寄ってください。 — Please be sure to stop by this store if you are nearby.
  • 計画の是非を全員で話し合った。 — We discussed together whether the plan was right or wrong.

2. Common pitfalls and similar expressions

• Adverb and noun uses
  • In an invitation, 是非 is an adverb meaning “by all means”; in 是非を話し合う, it is a noun meaning whether something is right or wrong.