Wordnet 3.0
NOUN (2)
1.
a person who knows or apprehends;
[syn: knower, apprehender]
2. a person who seizes or arrests (especially a person who seizes or arrests in the name of justice);
The Collaborative International Dictionary of English v.0.48:
Apprehender \Ap`pre*hend"er\, n.
One who apprehends.
[1913 Webster]
WordNet (r) 3.0 (2006):
apprehender
n 1: a person who knows or apprehends [syn: knower,
apprehender]
2: a person who seizes or arrests (especially a person who
seizes or arrests in the name of justice)