adverb, adverb taking the と particle, takes する

Usually written with kana alone, onomatopoeic or mimetic word.
  1. tightly (holding on), firmly, securely.
  2. strongly (built), solidly, sturdily, steadily.
  3. properly, well, sufficiently, hard (working, etc.), fully, completely.
  4. reliably, dependably, levelheadedly, shrewdly, wisely, cleverly.

Variations

Pronunciation Kanji Kana Is Common
 
 
 
 
しっかり
 
確り しっかり
 
聢り しっかり