perturb

From Late Middle English perturben (“to disturb (someone) mentally, disquiet; to cause disorder to (something), confuse; to hinder (something)”), from Old French perturber, and from its etymon Latin perturbāre, the present active infinitive of perturbō (“to confuse; to alarm, disturb, trouble, perturb”), from per- (intensifying prefix) + turbō (“to agitate, disturb, unsettle, perturb; to upset”) (from turba (“disorder, disturbance, turmoil”) (possibly from Ancient Greek τῠ́ρβη (tŭ́rbē, “confusion, disorder, tumult”), either from Pre-Greek, or Proto-Indo-European *(s)twerH- (“to agitate, stir up; to urge on, propel”)) + -ō (suffix forming infinitives of regular first-conjugation verbs)).