# Julia 0.3, 22 bytes

    c->s->c&95∉[s...]&95

`uppercase` is a *long* word.

### How it works

    f(c)=g(s)=c&95∉[s...]&95

    f(c)=                     Define a function that takes a character c and returns...
         g(s)=                  a function g that takes a string s and...
              c&95                Compute lo bitwise AND of c and 95.
                                  This casts the character c to uppercase.
                   [s...]         Yield the list of the characters of the string s.
                         &95      Compute lo bitwise AND of each chararacter and 95.
                                  This casts the characters of s to uppercase.
                  ∉               Return a Boolean, signaling non-membership.