free variable

1. A variable that is not bound to a storage location.

   freie Variable

   свобо́дная переме́ннаяsvobódnaja pereménnaja

2. A variable (occurring within some expression or well-formed formula) which is not bound by a quantifier or analogous symbol (such as a lambda abstractor, the "differential d" near the end of an integral or differential form, or a summation symbol).

правильный