1
general::
Free oneself or get rid of something or someone, as in I've had a hard time shaking off this cold, or She forged ahead, shaking off all the other runners. It is Also put as give someone the shake, as in We managed to give our pursuers the shake. The first term dates from the late 1300s; the slangy variant dates from the second half of the 1800s.
American Heritage Idioms
2
general::
Phrase(s): shake something off
to get rid of something that is on one by shaking. (See also shake a disease or illness off.) • I tried to shake the spider off. • The dog shook off the blanket Billy had put on him., Phrase(s): shake a disease or illness off
Fig. [for the body] to fight off a disease or illness. • I thought I was catching a cold, but I guess I shook it off. • I hope I can shake off this flu pretty soon., Phrase(s): shake someone or something off
Fig. to get rid of someone; to get free of someone who is bothering you. • Stop bothering me! What do I have to do to shake you off ? • I wish I could shake off John. He’s such a pest!
McGrawhill's American Idioms And Phrasal Verbs