pre·scrip·tive /prɪˈskrɪptɪv/
 (a.)規定的,指示的,慣例的
 Pre·scrip·tive a.
 1. Law Consisting in, or acquired by, immemorial or long-continued use and enjoyment; as, a prescriptive right of title; pleading the continuance and authority of long custom.
    The right to be drowsy in protracted toil has become prescriptive.   --J. M. Mason.
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 prescriptive
      adj 1: giving directives or rules; "prescriptive grammar is
             concerned with norms of or rules for correct usage"
             [syn: normative] [ant: descriptive]
      2: based on or prescribing a norm or standard; "normative
         grammar" [syn: normative]