動詞 detract:

1. take away a part from; diminish
   同義詞：take away

1. A little crack detracts from the value of the vase.
   小小的裂痕減損那個花瓶的價值。
2. His high voice and unpleasant appearance detract from his effectiveness as a speaker.
   說話語調高，加之外貌不太好看，有損于他作為演講者的影響。

de.tract

v.（動詞）
de.tract.ed,de.tract.ing,de.tracts
v.tr.（及物動詞）
To draw or take away; divert:
取走；分心，轉移：
例句：
They could detract little from so solid an argument.
他們從這如此堅實的論證中幾乎挑不出一點兒毛病

Archaic To speak ill of; belittle.
【古語】 誹謗；毀損
v.intr.（不及物動詞）
To undergo reduction in value, importance, or quality; become reduced, as in effect. Often used withfrom :
貶低，減損：降低價值，重要性或質量；降低效果。經(jīng)常與from 連用：
例句：
testimony that only detracts from the strength of the plaintiff`s case.
僅僅降低了原告案情有力的證詞

To divert or draw away qualities or a quality essential to the value, importance, or effect of something:
減損：分離或損害了決定某事價值，重要性或效果的特性：
例句：
a decorating scheme that detracts but does not enhance.
一個不但沒增色反而減色的裝修方案

來源：
Middle English detracten
中古英語 detracten
from Latin dôtrahere dôtr3ct- [to remove]
源自 拉丁語 dôtrahere dôtr3ct- [移走]
dô- [de-]
dô- [前綴，表.降低.]
trahere [to pull]
trahere [拉曳]
Sense 2, from Latin dôtr3ct3re [frequentative of] dôtrahere [to take away]
釋義2，源自 拉丁語 dôtr3ct3re [] dôtrahere的重復動詞 [取走]

【引伸】
detrac.tor
n.（名詞）