de·duct 
(dĭ-dŭkt)
(dĭ-dŭkt)v. de·duct·ed, de·duct·ing, de·ducts
v.tr.
1. To take away (a quantity) from another; subtract.
2. To derive by deduction; deduce.
v.intr.
To take away a desirable part: Poor plumbing deducts from the value of the house.
[Middle English deducten, from Latin dēdūcere, dēduct-, to lead away or down; see DEDUCE.]