from
Easton's 1897 Bible Dictionary
Concision
(Gr. katatome; i.e., "mutilation"), a term used by Paul
contemptuously of those who were zealots for circumcision (Phil.
3:2). Instead of the warning, "Beware of the circumcision"
(peritome) i.e., of the party who pressed on Gentile converts
the necessity of still observing that ordinance, he says,
"Beware of the concision;" as much as to say, "This circumcision
which they vaunt of is in Christ only as the gashings and
mutilations of idolatrous heathen."