しっかり

Usually written in kana. Kanji spelling 確り

tightly (holding on); firmly; securely; strongly (built)

JLPT N4 Also written 聢り

Meaning

advadv-tovs
tightly (holding on); firmly; securely
advadv-tovs
strongly (built); solidly; sturdily; steadily
advadv-tovs
properly; well; sufficiently; hard (working, etc.); fully; completely
advadv-tovs
reliably; dependably; levelheadedly; shrewdly; wisely; cleverly