Definition of "left"

left¹

/ˈlɛft/

adjective
comparative more left or lefter, superlative most left or leftmost
1. Designating the side of the body toward the west when one is facing north; the side of the body on which the heart is located in most humans; the opposite of right. This arrow points to the reader's left: ←
2. (geography) Designating the bank of a river (etc.) on one's left when facing downstream (i.e. facing forward while floating with the current); that is, the north bank of a river that flows eastward. If this arrow: ⥲ shows the direction of the current, the tilde is on the left side of the river.
  Quotations
  The following dispatch has been received from Viceroy Alexieff, dated Mukden, March 22:“Gen. Mitchenkow reports that on March 17 our scouts approached Anju and observed on the left bank of the Ching Chong river, opposite Anju, retrenchments made by the enemy.
  1904 March 23 , Viceroy Alexieff, quotee, “Waiting for the First Collision in the Yalu Region”, in St. Louis Post-Dispatch‎, volume 56, number 215, St. Louis, page 2, column 2
3. (politics) Left-wing; pertaining to the political left.
  Quotations
  It should be noted that there is now no intelligentsia that is not in some sense "Left". Perhaps the last right-wing intellectual was T. E. Lawrence. Since about 1930 everyone describable as an “intellectual” has lived in a state of chronic discontent with the existing order.
  1941, George Orwell, The Lion and the Unicorn
adverb
not comparable
1. On the left side.
2. Towards the left side.
3. Towards the political left.
noun
plural lefts
1. The left side or direction.
2. (politics) The left-wing political parties as a group; citizens holding left-wing views as a group.
3. The left hand or fist.
4. (boxing) A punch delivered with the left fist.
  Quotations
  The world 'as got me snouted jist a treat; Crool Forchin's dirty left 'as smote me soul.
  1915, C.J. Dennis, The Songs of a Sentimental Bloke, published 1916, page 13
5. (surfing) A wave breaking from left to right (viewed from the shore).

left²

verb
1. simple past and past participle of leave (“depart, separate from; (cause or allow to) remain”).
  Quotations
  Afore we got to the shanty Colonel Applegate stuck his head out of the door. His temper had been getting raggeder all the time, and the sousing he got when he fell overboard had just about ripped what was left of it to ravellings.
  1913, Joseph C. Lincoln, chapter 8, in Mr. Pratt's Patients
  Shepard: What's wrong with your assistant?Dr. Warren: Manuel has a brilliant mind, but he's always been a bit... unstable. Genius and madness are two sides of the same coin.Dr. Manuel: Is it madness to see the future? To see the destruction rushing towards us? To understand there is no escape? No hope? No, I am not mad. I'm the only sane one left!Dr. Warren: I gave him an extra dose of his meds after the attack.
  2008, BioWare, Mass Effect (Science Fiction), Redwood City: Electronic Arts, PC, scene: Eden Prime

left³

verb
1. simple past and past participle of leave (“permit”).