From Wikipedia (and pointed out to me by a reader):

Lagom (pronounced [ˈlɑ̀ːɡɔm]) is a Swedish word with no direct English equivalent, meaning “just the right amount”.

The Lexin Swedish-English dictionary defines lagom as “enough, sufficient, adequate, just right”. Lagom is also widely translated as “in moderation”, “in balance”, “optimal” and “suitable” (in matter of amounts). Whereas words like “sufficient” and “average” suggest some degree of abstinence, scarcity, or failure, lagom carries the connotation of appropriateness, although not necessarily perfection. The archetypical Swedish proverb “Lagom är bäst”, literally “The right amount is best”, is translated as “Enough is as good as a feast” in the Lexin dictionary. That same proverb is translated as “There is virtue in moderation” in Prismas Stora Engelska Ordbok (1995)