(rt, rt) noun
1. The underground portion or descending axis of a plant, which absorbs moisture, obtains or stores nourishment, and provides support. It differs from the stem in that it branches irregularly and lacks joints or leaves.
2. Loosely, any underground growth, as a tuber or bulb.
3. One of certain other growths serving for attachment, support, etc., as in the ivy or mistletoe.
4. That from which anything derives origin, growth, or life and vigor: Money is the root of evil; Industry is the root of prosperity.
5. An antecedent; ancestor.
6. Some rootlike part of an organ or struture: the root of a tooth or nerve.
7. Ling. A morpheme serving as the common center or basic constituent element of a related group of words, as know in unknown, knowledge, knowable, and knowingly. A root to which affixes or other morphemes may be added directly is equivalent to a stem.
8. Math. A quantity that, taken a specified number of times as a factor, will give another quantity called its power: 2 is the fourth root of 16. The number of times the root is thus taken as a factor is called its index, and roots are named from the indices, the words square root and cube root being often used for second and third root.
9. A tone on which a chord is built up.
—v.i.
1. To put forth roots and begin to grow; take root.
2. To be or become firmly fixed or established.
—v.t.
3. To fix or implant by or as by roots.
4. To pull, dig, or tear up by or as by the roots; extirpate; eradicate: with up or out. [OE rōt <ON rōt]

(rt, rt) v.t.
1. To turn up or dig with the snout or nose, as swine.
—v.i.
2. To turn up the earth with the snout.
3. To search for something; rummage.
4. To work hard; toil. [OE wrōtan root up <wrōt snout]

(rt, rt) v.i. U.S. Colloq.
To cheer for or encourage a contestant: with for: He rooted for Harvard. [Prob. var. of ROUT³]

(rt, rt), Elihu,
1845–1937, U.S. lawyer and statesman.