Etymology
First attested in 1841; borrowed from Medieval Latin dissimilātus, perfect passive participle of dissimilō (see -ate (verb-forming suffix)), hypercorrected form of Classical Latin dissimulō, from dis- + simulō, from similis (“similar, the same as”); the vocalism was perhaps influenced by assimilate, compare dissimulate. Cognate with French dissimiler; doublet of dissemble, dissimulate, and dissimule.