Re*act"ive*ly

from The Collaborative International Dictionary of English v.0.48

Reactive \Re*act"ive\ (r[-e]*[a^]kt"[i^]v), a. [Cf. F.
   r['e]actif.]
   Having power to react; tending to reaction; of the nature of
   reaction. -- {Re*act"ive*ly}, adv. -- {Re*act"ive*ness}, n.
   [1913 Webster]