Bespoke is an adjective for anything commissioned to a particular specification. "Custom-made", "made to order", "made to measure" and sometimes "hand-made" are near-synonyms. "Off-the-shelf" and in clothing "ready-to-wear" are the opposites. Modding is a slang related term, mostly used to refer to personalization after manufacture.
The word bespoke is derived from the verb to bespeak, to "speak for something", in the specialised meaning "to give order for it to be made" or commission, first cited from 1583 by the OED, with the adjective in its alternative form "bespoken" first quoted from 1607 in this sense. The term is generally more prevalent in British English than American English, which tends to use "custom" instead, as in custom car, custom motorcycle etc.
Specific uses include:
- Bespoke medicine, a movement to better fit treatment to the individual patient
- Bespoke software, software written to the specific requirement of a customer
- Bespoke tailoring, men's clothing made to the individual measurements of the customer
- OED: "Bespeak", 5, first cited from 1583, and "Bespoken" 2.