1. I-adjective (keiyoushi)

   1.

   hard; solid; tough

2. 2.

   stiff; tight; wooden; unpolished (e.g. writing)

3. 3.

   strong; firm (not viscous or easily moved)

Example sentences

• トムは頭が固い。

  Tom is stubborn.

• 固いこと言うなよ。

  You don't have to be so formal.