de·tract 
(dĭ-trăkt)
(dĭ-trăkt)v. de·tract·ed, de·tract·ing, de·tracts
v.tr.
To draw or take away; divert: They could detract little from so solid an argument.
v.intr.
To reduce the value, importance, or quality of something. Often used with from: testimony that only detracts from the strength of the plaintiff's case.
[Middle English detracten, from Latin dētrahere, dētract-, to remove : dē-, de- + trahere, to pull.]
de·tractor n.