楽しい

1. Origins, structure, and basic meaning

• Structure: 楽しい, read たのしい, joins the enjoyment stem 楽し with the i-adjective ending い.
• Basic usage: It expresses present enjoyment in 時間は楽しい and past enjoyment in 遠足は楽しかった.

2. Common pitfalls and similar expressions

• Forms and inflection
  • The past form is 楽しかった and the negative is 楽しくない, so attach endings to the correct stem.