Adverb
Verb (する)
Onomatopoeic
Usually written in kana
1. tightly (holding on); firmly; securely
両手でしっかり持ってください。Please hold it firmly with both hands.
2. strongly (built); solidly; sturdily; steadily
うん、聞いてた通り、しっかりしたキッチンだね。Yeah, just as I heard, it's a solid kitchen.
3. properly; well; sufficiently; hard (working, etc.); fully; completely
このことは、しっかり説明したわよね。I explained this properly, didn't I?
4. reliably; dependably; levelheadedly; shrewdly; wisely; cleverly
あなたはしっかりした考え方をしている。You have a levelheaded way of thinking.