An Etymological Dictionary of the German Language/Annotated/sicher
sicher, adjective, ‘sure, certain, trusty,’ from Middle High German sicher, Old High German sihhū̆r, ‘careless, unconcerned; sure, protected, confident’; to these are allied Old Saxon and Anglo-Saxon sicor, ‘free from guilt and punishment,’ Middle English sîker, Dutch zeker (Old High German sihhorô(illegible text), ‘to justify, protect, promise, vow,’ Old Saxon sicorôn, ‘to set free’). It is based on the common West Teutonic loan-word Latin sêcûrus (phonetic intermediate form sĕcûrus, the accent of which was Germanised when the word was borrowed); compare Italian sicuro, French sûr. The term was naturalised in German before the 7th century, as is shown by the permutation of k to ch. Was it first introduced through the medium of legal phraseology? Compare Old High German sihhorôn, ‘to justify, purgare.’