An Etymological Dictionary of Astronomy and Astrophysics

To cause a small → deviation in the → behavior of a → physical system, e.g. in the → orbit of a planet.

Etymology (EN): O.Fr. perturber, from L. perturbare “to confuse, disorder, disturb,” from per- “through” + turbare “disturb, confuse,” from turba “turmoil, crowd,” turbidus “muddy, full of confusion.”

Etymology (PE): Parturidan, from par-, related to pirâ- (cf. Av. per- “to pass across, through”) + turidan “to run away, be very much ashamed,” tur “withdrawal, flight;” Lori, Laki tur
“restive, disobedient,” Laki turyâyen “to get angry, lose one’s temper,”
probably cognate with L. turba, as above.