björntjänst

björn (“bear”) +‎ tjänst (“service, favor”), used since 1891. Compare Danish bjørnetjeneste, German Bärendienst, and similar forms in other languages. From a French fable (L’Ours et l’Amateur des jardins by Jean de La Fontaine) in which a tame bear wants to do his master a favor by hitting the fly who sat down on the master's forehead, but hits the fly so hard that the master too is killed.

björntjänst c

1. a disservice, a mistaken kindness, a misguided helpfulness, an attempted favor which turns out to be detrimental, or at least causes more damage than it helps

   I alla händelser är det uppenbart, att man gör de människor som nu tillhöra jordbruksbefolkningen samt deras barn en björntjänst genom att tvinga dem att förbli jordbruksbefolkning, om de kunna få bättre villkor i andra sysselsättningar.

   In any case it is obvious, that we will do those people who now belong to the peasantry and their children a disservice by forcing them to to remain peasants, if they could get better conditions in other occupations.

• otjänst

• björntjänst in Svenska Akademiens ordlista över svenska språket (13th ed., online)
• björntjänst in Svenska Akademiens ordbok online.
• björntjänst in Elof Hellquist, Svensk etymologisk ordbok (1st ed., 1922)
• björntjänst in Walter E. Harlock, Svensk-engelsk ordbok : skolupplaga (1964)