How Well Do You Know English Slang?
"custom or custom-made, made to order," of goods, as distinguished from ready-made, 1755, the same sense found earlier in bespoken (c.1600), past participle of bespeak, in a sense of "to speak for, to arrange beforehand," a sense attested in bespeak from 1580s. Now usually of tailored suits.
Old English besprecan "speak about, speak against, complain," from be- + sprecan "to speak" (see speak). A common Germanic compound (cf. Old Saxon bisprecan, Dutch bespreken, Old High German bisprehhan, German besprechen); originally "to call out," it evolved a wide range of meaning in English, including "speak up," "oppose," "request," "discuss, "arrange," and "to order (goods)" (1580s).
The connection of the senses is very loose; some of them appear to have arisen quite independently of each other from different applications of BE- pref. [OED]