From The Collaborative International Dictionary of English v.0.48 [gcide]:
Purchase \Pur"chase\ (?; 48), v. t. [imp. & p. p. Purchased;
p. pr. & vb. n. Purchasing.] [OE. purchasen, porchacen, OF.
porchacier, purchacier, to pursue, to seek eagerly, F.
pourchasser; OF. pour, por, pur, for (L. pro) + chacier to
pursue, to chase. See Chase.]
1. To pursue and obtain; to acquire by seeking; to gain,
obtain, or acquire. --Chaucer.
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That loves the thing he can not purchase. --Spenser.
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Your accent is Something finer than you could
purchase in so removed a dwelling. --Shak.
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His faults . . . hereditary
Rather than purchased. --Shak.
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2. To obtain by paying money or its equivalent; to buy for a
price; as, to purchase land, or a house.
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The field which Abraham purchased of the sons of
Heth. --Gen. xxv.
10.
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3. To obtain by any outlay, as of labor, danger, or
sacrifice, etc.; as, to purchase favor with flattery.
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One poor retiring minute . . .
Would purchase thee a thousand thousand friends.
--Shak.
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A world who would not purchase with a bruise?
--Milton.
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4. To expiate by a fine or forfeit. [Obs.]
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Not tears nor prayers shall purchase out abuses.
--Shak.
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5. (Law)
(a) To acquire by any means except descent or inheritance.
--Blackstone.
(b) To buy for a price.
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6. To apply to (anything) a device for obtaining a mechanical
advantage; to get a purchase upon, or apply a purchase to;
as, to purchase a cannon.
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From WordNet (r) 3.0 (2006) [wn]:
purchasing
n 1: the act of buying; "buying and selling fill their days";
"shrewd purchasing requires considerable knowledge" [syn:
buying, purchasing]