Back n. : A large shallow vat; a cistern, tub, or trough, used by brewers, distillers, dyers, picklers, gluemakers, and others, for mixing or cooling wort, holding water, hot glue, etc.

Back n. : A ferryboat. See Bac, 1.

Back n. : In human beings, the hinder part of the body, extending from the neck to the end of the spine; in other animals, that part of the body which corresponds most nearly to such part of a human being; as, the back of a horse, fish, or lobster.

Back n. : An extended upper part, as of a mountain or ridge.

Back n. : The outward or upper part of a thing, as opposed to the inner or lower part; as, the back of the hand, the back of the foot, the back of a hand rail.

Back n. : The part opposed to the front; the hinder or rear part of a thing; as, the back of a book; the back of an army; the back of a chimney.

Back n. : The part opposite to, or most remote from, that which fronts the speaker or actor; or the part out of sight, or not generally seen; as, the back of an island, of a hill, or of a village.

Back n. : The part of a cutting tool on the opposite side from its edge; as, the back of a knife, or of a saw.

Back n. : A support or resource in reserve.

Back n. : The keel and keelson of a ship.

Back n. : The upper part of a lode, or the roof of a horizontal underground passage.

Back n. : A garment for the back; hence, clothing.

Back a. : Being at the back or in the rear; distant; remote; as, the back door; back settlements.

Back a. : Being in arrear; overdue; as, back rent.

Back a. : Moving or operating backward; as, back action.

Back v. i. : To get upon the back of; to mount.

Back v. i. : To place or seat upon the back.

Back v. i. : To drive or force backward; to cause to retreat or recede; as, to back oxen.

Back v. i. : To make a back for; to furnish with a back; as, to back books.

Back v. i. : To adjoin behind; to be at the back of.

Back v. i. : To write upon the back of; as, to back a letter; to indorse; as, to back a note or legal document.

Back v. i. : To support; to maintain; to second or strengthen by aid or influence; as, to back a friend.

Back v. i. : To bet on the success of; -- as, to back a race horse.

Back v. i. : To move or go backward; as, the horse refuses to back.

Back v. i. : To change from one quarter to another by a course opposite to that of the sun; -- used of the wind.

Back v. i. : To stand still behind another dog which has pointed; -- said of a dog.

Back adv. : In, to, or toward, the rear; as, to stand back; to step back.

Back adv. : To the place from which one came; to the place or person from which something is taken or derived; as, to go back for something left behind; to go back to one's native place; to put a book back after reading it.

Back adv. : To a former state, condition, or station; as, to go back to private life; to go back to barbarism.

Back adv. : (Of time) In times past; ago.

Back adv. : Away from contact; by reverse movement.

Back adv. : In concealment or reserve; in one's own possession; as, to keep back the truth; to keep back part of the money due to another.

Back adv. : In a state of restraint or hindrance.

Back adv. : In return, repayment, or requital.

Back adv. : In withdrawal from a statement, promise, or undertaking; as, he took back0 the offensive words.

Back adv. : In arrear; as, to be back in one's rent.

Example:
When does neck and Back pain start to occur during pregnancy?

Taxonomy
back pain, Diagnosis, treatment options, low back pain, Treatment, Minimally invasive, painful symptoms, Degenerative Disc Disease, leg pain, new technology, physician locator, doctor, Herniated Disc, Lumbar spinal fusion, Animations, back pain treatment, numbness, weakness.

Defination from the web:
back pain including symptons, causes, treatment options, doctor database, and more.