noun

1. a usual practice or habitual way of behaving; habit
2. 1. a social convention carried on by tradition and enforced by social disapproval of any violation
   2. such practices, collectively
3. under feudalism, a service, rent, etc. regularly paid to a lord
4. 1. duties or taxes imposed by a government on imported and, occasionally, exported goods
   2. the government agency in charge of collecting these duties, or any of its offices
5. 1. the regular support or patronage of a business establishment
   2. customers as a group
6. Law such usage as by common consent and long-established, uniform practice has taken on the force of law

Etymology: ME < OFr costume < L consuetudo < consuescere, to accustom < com-, intens. + suescere, to become accustomed < suere, to be accustomed, akin to suus, one's own: for IE base see suicide

adjective

1. made or done to order or, sometimes, made extra fine, as if to order
2. making things to order, or dealing in things made to order a custom tailor