词根：err(arr) = to wander（漫游）
来源：①来源于拉丁语 errare 徘徊，arr是它的变形。如果你“漫游”的脱离了正道，太离谱，当然会“犯错误”，所以该词根所构成的词汇有很多都含有“犯错”的含义；②来源于拉丁格言：Errare humanum est．即：人非圣贤，孰能无过；③来源于字母的含义，e 代表“眼睛”，r 代表“树枝”，理解为：眼看着大树的树枝不断漫无边际地双倍向外生长。
同义词根有来自拉丁语的plan和来自希腊语的vag,异形同义词根是：-vag- 徘徊，迷失。
同源词：
1. arrant
adj.足的；臭名昭著的，声名狼藉的
arrant thief 臭名昭著的小偷
arrant fool 十足的傻瓜
arranf rogue 十足的恶棍
arrant nonsense 一派胡言
2. err
v.犯错：出差错
3. errand
n.差事
a fool's errand 白跑腿的差事
errand boy 供差遣的童仆
run errands 跑腿
4. errant
adj.犯错误的，诶人歧途的
errant husband 犯了错误的丈夫
5. erratic
adj.古怪的；无规律的；无固定路线的
erratic star 运行轨道不定的星星
6. erratum
n.书写错误，印刷错误
errata (erratum的复教)
7. erroneous
asdj.错误的，不正确的
8. error
n.错误，过失，失误
clerical error 誊写工作中的笔误
fall into error 误入歧途
printer's errors 印刷错误
error of judgment 判断错误
9. unerring
adj.反正确无误的；没有偏差的 *un(=not)
fire with unerring aim 瞄准射击
strike an unerring blow 击中
10. oberrant
adj.超乎党轨的；变态的；异常的（漂离）ab(=away)
oberrance n.越轨；逸出
aberration n.越轨；恍惚；错乱
11. inerrant
adj. 无错误的 in(=not)
inerrantic adj.非反复无常的；有规律的；固定的
12. aberration [脱离某物徘徊ab(=from)+err(=wander)]
n. the state of being abnormal; an abnormal act; failure of rays to focus 脱离常规；越轨；像差（焦点不准确而造成的物象模糊）
aberrant adj.脱离常规的；越轨的；
An aberration in the lens caused the telescope to reveal a flawed image. 镜头出现了像差，导致望远镜上的图像有些走样。
后缀：-end [名词后缀]
构成抽象名词，大多见于数学术语，亦作-and
dividend 被除数
multiplicand 被乘数
addend 加数
subtrahend 减数
minuend 被减数
legend 传奇，传说
errand 使命
词根词缀：doul-, dulo-, dul-
【来源及含义】Greek: slave, servile, slavish; servitude; serving
【相关描述】A doula supports a woman and her family in achieving the kind of birth that they desire. A doula works in homes, hospitals, and birth centers; and gives, emotional, physical, and informational support. A careprovider, be he/she a midwife, OB/gyn, or family practitioner, will take care of a woman's prenatal care and birth. A doula is supposed to ensure that someone is always available to look after the mother-to-be emotionally. These objectives are facilitated by communication between the laboring woman, her partner, and her clinical care providers.
As a supportive companion (other than a friend or loved one) a doula is professionally trained to provide birth-labor support. She performs no clinical tasks. A doula also refers to lay women who are trained or experienced in providing postpartum care—mother and newborn care, breastfeeding support and advice, cooking, child care, errands, and light cleaning—for the family. To distinguish between the two types of doulas, one may refer to "birth doulas" and "postpartum doulas".