teething /ˈtiːðɪŋ/noun 1forms 1phrases 2 noun1 •The eruption, through the gums, of the milk teeth; dentition.But with night feedings and night teethings, often the greatest challenge of all for a young mother is simply fatigue. — 2009 formsteethings Phrases with teething teething problemA problem encountered with any new and untried product, system, or venture. teething troublesProblems that are to be expected with any new and untried product, system, or venture.