前缀ob-(oc-,of-,op-,os-,o-)词源、意思和例词
词源：
前缀ob-来源于拉丁介副词ob，原意是“toward"，在构词当中又引申出“against,inversely”等意思，还有“to, in the way, over, away, completely,intensive”等含义。ob-是个原生词缀，一般与拉丁词根缀合，所构成的派生词的词性取决于词根或后缀的属性。由于语音的同化作用，ob-在c,f,p前面，变成oc-,of-,op-。在元音字母及其它辅音字母前，ob-形态不变。
每个前缀的纯英语来源解释：
ob-
prefix meaning "toward, against, across, down," also used as an intensive, from Latin ob "toward, to, over against, in the way of, by reason of, about, before, in front of," from PIE root *epi, also *opi "near, against" (see epi-).
oc-
assimilated form of ob- before -c-.
of-
assimilated form of ob- before -f-.
op-
assimilated form of ob- before -p-.
os-
frequent form of ob- before -c- and -t- in words from Latin.
现在对这几个前缀的含义整理如下：
1．逆着…，和…敌对，和…相反
oppress, opprobrium
2．向着…，给…
obnoxious, opportune
3．妨碍地
officious, obsequious, obsession
4．越过，盖住
obscene, obfuscate, obscure
5．远远地，消失
obviate, omission
6．表强调[完全，干脆，厉害地，继续]
obese, obdurate, obeisance
另外，前缀ob-还有很多变形。
1．oc-[在辅音字母c之前]
occult, occupied
2．of-[在辅音字母f之前]
offensive, officiator
3．op- [在辅音字母p之前]
opponent, inopportune
4．os-[在辅音字母t之前]
ostensible, ostentatious
5. o- [在辅音字母m之前]
此外，前缀ob-还有一些同义前缀，也有“反对，抵抗”的意思,这些词缀是：
1.officiate [of<ob( =intensive) +
vt. at+sth perform the duties of an office or position; preside 行使职务，行使职权；主持 oflice 事务所；政府机关 officer 军官 officiator 主婚人 offcial 正式的，公务的；公务员，官员
举例：A Unitarian minister officiated at his funeral.
一位一神论派的牧师主持了他的葬礼。
2.oppress [op<ob( =against, intensive) +press( =press)逆着某物压挤]
vt. keep down by unjust or cruel government; rule unjustly or cruelly; weigh heavily on 压迫，压制；用暴政统治；使烦闷，施加重压
oppression 压制，压抑；迫害 oppressor 压制者，暴君 oppressive 压制的,压迫的；烦闷的，窒息的
举例： Organized religion is often used to oppress people, in my view
我认为，组织化的宗教往往被用来压制人民。
3.obliterate [ob( =against) +liter( =letter)逆着文字走]
vt. rub or blot out; remove all signs of; destroy 擦掉；消除痕迹；抹杀
obliteration 删除；抹杀
举例： The crows completely obliterated his corn crop this year.
乌鸦把他今年收获的玉米消灭得一千二净。
4.obese [ob( =intensive) +es<ed( =eat)多多地吃]
vt. very fat 很胖的，非常胖的 obesity 肥胖，肥大
举例： Nearly 20% all Americans are now classified obese
现在美国人中有近20%可划分为肥胖人群。
5.obligate [ob( =intensive) +lig( =bind)用力地捆]
vt. sb+to do bind someone legally 使负义务；强使 obligation 义务，责任
obligatory 有义务的：要求的，必须的 oblige 使不得不…；使感谢
举例：A typical rental lease obligates the landlord to make any needed repairs.
典型的租赁合同上规定，房东必须负责任何必要的维修。
6.obnoxious [ob( =to) +nox<noc( =hurt)给某人痛苦]
adj. very disagreeable, very unpleasant, hateful 非常讨厌的．非常不愉快的,可憎的
举例： That obnoxious little boy just kicked me in the shin!
那个可恶的小男孩儿踢到了我的胫骨！
7.obviate [ob( =away) +vi<via( =carry, way)把某物搬得远远的，使消失]
vt. get rid of; clear away; prevent by effective measures 排除（危险、困难等）,清除；消除；防患于未然
obvious 明白的 obviously 明显地
举例： Satellite TV obvistes the need for an outside TV antenna.
有了卫星电视，就不需要室外电视天线了。
8.officious [of<ob( =in the way) +fic( =do, make)使妨碍]
adj. very fond of giving unwelcome services or advice 妤出主意的,多管闲事的
举例：The government required us to use their somewhat officious translator.
政府要求我们用那个爱多管闲事的翻译官。
9.obdurate [ob( =intensive) +dur( =last)继续持续]
adj. stubborn, obstinate, inflexible 顽固的，固执的，没有融通性的
obduracy 倔强，顽固，执拗
举例：He's extremely obdurate-offending people and never apologizing afterward.
他非常固执，冒犯了别人之后从小道歉。
10.occult [oc<ob( =intensive) +cul<cel( =hide)严严实实地藏着的]
adj. hidden, secret, mysterious; supernatural, magical 隐藏的．秘密的；超自然的；神秘的
举例： l've long been a student of occultarts.
我学了很长时间的秘术。
11.opportune [op<ob( =toward) +port( =carry)向着某东西搬运]
adj. suitable,favorable; good for a purpose; done or coming at a favorable time 适时的，恰好的；适合目的的；适宜的，时机好的
opportunity 机会，良机 opportunism 机会主义 opportunist 机会主义者
举例： This is an opportune time for me to retire-at the end of the project.
这项工程完成之时正是我退休的好时机。
12.ostensible [os<ob( =against, over) +tens( =stretch)向某事物的反方向拉长]
adj. put forward in an attempt to hide the real reason; apparent; pretended 表面上的；外表上的；假装的
ostensibly 表面上
举例： The ostensible reason for their divorce was "irreconcilable differences".
他们离婚的表面原因是“无法调解的矛盾”。
13.ostentatious [os<ob( =against, over) +tent(=stretch)向某事物的反方向拉长]
adj. done for unnecessary display; liking to attract notice 卖弄的，夸耀的；豪华的，铺张的
ostentation 夸耀，虚饰，卖弄 ostentatiously 卖弄地
举例： We want an elegant but not ostentatious wedding.
我们希望举行一个体面而不铺张的婚礼。
14.obeisance [ob( =intensive) +eis<aud( =hear) 很听话]
n. ～ to deep bow of respect; homage; obedience, submission 敬礼；尊敬；服从
举例： My sister pays devoted obeisance to an Indian guru, of all things.
我妹妹全心全意地尊崇一位印度教领袖。
15.obscene [ob( =against,over) +scen( =set)逆着某物、超越某种程度的放置]
adj. morally disgusting; likely to corrupt and deprave by regarding or describing sex indecently（话、想法、书籍、画等）伤风败俗的；猥亵的，淫秽的，下流的
obscenity 猥裘，淫秽；猥亵的言语（行为）
举例：Different people have ditferent opinions about what is obscene.
对于什么是淫秽，不同的人有小同的看法。
16.obsequious [ob( =in the way) +sequ( =follow) 追随、奉承让人感到碍手碍脚]
adj. too eager to obey or serve; showing excessive respect from hope of reward or advantage 奉承的；拍马屁的
举例： lt's difficult for me to trust obsequious people. 我很难信任阿谀奉承的人。
17.opprobrium [op<ob( =against) +pro( =forth) +br<fer( =carry) 和某人逆着向前搬运]
n. the disgrace or infamy attached to conduct viewed as grossly shameful; scom; reproach 耻辱，不名誉；蔑视；责难 opprobrious 侮辱的，辱骂的；丢脸的，羞耻的
举例： Many Repubticans said that Clinton brought unprecedented opprobrlum to his office.
很多共和党人说，克林顿给他的职位带来了前所未有的耻辱。
18.obloquy [ob( =against) +loqu(=say)和某人敌对着说]
n. bad words spoken of a person or thing; ill repute,disgrace 诽谤，破口大骂,辱骂；污名，不名誉
举例： His reputation was damaged by the obloquy heaped upon him in the press.
新闻媒体对他的大肆诽谤损害了他的声誉。
19.obsession [ob( =in the way) +sess( =sit)成为妨碍地坐着]
n. with ～ the act of an evil spirit in possessing or ruling a person; the state of being ruled by an idea. desire, emotion, etc.;a fixed idea which takes possession of one's mind 着魔，迷住；摆脱不了的情感
obsess（妄想、固有观念等）萦绕心头，不停地困扰 obsessive 困扰人的
举例： Eating is my hobby. Shopping is my obsession!
呓东西是我的爱好，购物让我着迷！
20.obtrude [ob( =in the way, intensive) +
vt. sth+on+sb push oneself, one's opinions, etc. forward when unwanted 强求，强行；伸出，突出
vi. on+sth force oneself upon others 强行进入，闯入；打扰
obtrusive 鲁莽的 obtrusion 强迫接受；闯入 obtrusively 冒失地
举例： l'm sick of that guy obtruding his opinions upon us at every turn.
我对经常把自己的意见强加给我们的那个人感到厌烦。