Compounds of にこ

• にこり
  (adv,adv-to) (on-mim) smile (sweetly)
  grin
• にこっと
  (adv) pleasantly smiling
• にこやか
  (adj-na,n) smiling
  (P)
• にこよん
  (n) day laborer (slang term)
• 陰にこもる
  (exp) (1) to stay bottled up inside oneself
  to be introverted
  (2) to have a melancholic appearance, atmosphere (of a person, object, place)
  to have a gloomy appearance
• にこっと笑う
  (exp,v5u) to smile pleasantly
• 蛸壺にこもる
  (exp) to be trapped in an octopus pot
• 鮹壷にこもる
  (exp) to be trapped in an octopus pot
• 用心するにこしたことはない
  (exp) better safe than sorry
  one should err on the side of caution