前缀 sub-(suc-,suf-,sug-,sum-,sup-,sur-,sus-) = under
前缀sub-来源拉介词sub,意为“under,from under”等，表示“在下”的位置或“自下而上”的运动。作为原生前缀，sub-出现在许多12世纪后引进的拉丁借词中，sub-依然遵守拉丁读音规则，接受词根首字母的同化产生出suc-,suf-,sug-,sum-,sup-,sur-,sus-,su-等变形异体。但在16世纪以后，sub-可作为活性派生词缀与各种语源的单词结合构成新词。在这些派生词中，sub-没有异体，而意思却有所引申。除under之外，它还可以表示“secondary, slightly,in place of, precisely"等含义。派生前缀sub-可以与名词、形容词、动词等结合。当他作为介词性前缀与名词结合时，可能改变词基单词的词性。与包含sub- 的拉丁借词相比，由派生前缀sub- 构成单词数量更多。
另一词源：刘毅英语字根字典介绍前缀sub-是由sup-演变而来，其比较级为super,最高级是supreme,Sub-原味“高”的意思，如super,supreme是指“以上；极度；超越”之意。依照sub-本来的意思“高”演变而来的自由sublime（崇高的；是崇高）。变化形：suc-,suf-,sug-,sum-,sur-,sus-" 。
英语词源：
word-forming element meaning "under, beneath; behind; from under; resulting from further division," from Latin preposition sub "under, below, beneath, at the foot of," also "close to, up to, towards;" of time, "within, during;" figuratively "subject to, in the power of;" also "a little, somewhat" (e.g. sub-horridus "somewhat rough").
This is said to be from PIE *(s)up- (perhaps representing *ex-upo-), a variant form of the root *upo- "from below," hence "turning upward, upward, up, up from under, over, beyond" (cf. Sanskrit upa "near,under, up to, on," Greek hypo "under," Gothic iup, Old Norse, Old English upp "up, upward," Hittite up-zi "rises"). The Latin word also was used as a prefix and in various combinations.
In Latin assimilated to following -c-, -f-, -g-, -p-, and often -r- and -m-. In Old French the prefix appears in the full Latin form only "in learned adoptions of old Latin compounds" [OED], and in popular use it was represented by sous-, sou-; cf. French souvenir from Latin subvenire, souscrire (Old French souzescrire) from subscribere, etc.
The original meaning is now obscured in many words from Latin (suggest, suspect, subject, etc.). The prefix is active in Modern English, sometimes meaning "subordinate" (as in subcontractor); "inferior"(17c., e.g. subhuman); "smaller" (18c.); "a part or division of" (c.1800, e.g. subcontinent).
以下是sub- 及其变体的含义：
1．红…底下，在…下边
subordinate, subservient, subsidiary
2．下位，副，一点，稍许
subtitle, subeditor, subacid
3．代替…
supplant, subaltern
4．精密地，细致地
subcommittee, subdivide, succinct
另外，前缀sub还有以下多种变形。
1．suc(在辅音字母c前)
succumb, succor
2．suf(在辅音字母f前)
suffrage, suffocate
3.sug(在辅音字母g前)
suggestion
4.sum(在辅音字母m前)
summons
5．sup(在辅音字母p前)
supplement, suppress
6.sur(在辅音字母r前)
surrogate, surreptitious
7．sus(在辅音字母c．p，t前)
susceptible, suspension, sustenance
此外，前缀sub有一些同义前缀，也有“在底下，在下边”的意思，还有一些意为“在上边”的反义前缀。
I．同义前缀
under
II．反义前缀
up
例句：
1.submissive [(sub( =under) +
adj. be～to yielding to the control or authority of another; meek 服从的，顺从的；柔顺的，温顺的 submit 服从，投降，屈服；提交 submission 服从，投降
举例： Rather than being submissive or aggressive, it's healthier to be assertive.
比起顺从或挑衅，坚持己见要更有益于身心。
2.subordinate [(sub( =under) +
adj. be～to inferior to or placed below another in rank,power,importance,etc. 地位、阶级等低的；下级的；从属的
n. person in a subordinata position 下级，从属者，部下
vt. place in a subordinate position 把…列入下级，使从属
subordination 下级，从属 subordinative 从属的
举例： If you speak to my subordinate, he can get the answer for you.
如果你跟我的下属讲，他会给你一个答复的。
3.subsequent [(sub( =under) +sequ（=follow）在下面（尾部）接着发生]
adj. be～to coming after; following in time, place, or order 后续的；以后的
subsequently 此后，其后，随后 subsequence 后继
举例： Subsequent tests revealed that she was suffering from pleurisy.
接下来的检查结果证明她患了胸膜炎。
4.suffrage [(suf<sub( =under) +frag( =break, loud applause)称赞到底]
n. franchise, right of voting in political elections; vote, consent expressed by voting 授票权，选举权；投票；赞成票
举例： Suffrage is constitutionally guaranteed to all non-criminal adults.
宪法保障所有不违法的成年人都有选举权。
5.supplement [sup<sub( =under) +
vt. sth+with+sth make up for a lack or deficiency 补充
n. something added 补充，增补；附录，增刊
supplementary 补充的，追加的；补角的
举例： Most breakfast cereals contain a host of vitamin and mineral supplements.
大部分的早餐谷类食品中都含有大量的维生素和矿物质添加剂。
词根：
1.miss(=send)
commission 委任：手续费；委员会 *com( =together)
intermission 中止，间断；休息时间 *inter( =between)
surmise 推测 *sur<super( =over)
2.ordin(=order)
ordination 种职授任仪式；排列
coordinate 同等的，同级别的；(pl.)（数学）坐标 *co<com(=together)
ordain （神、命运等）注定
3.sequ(=follow)
sequent 连续的；作为结果产生的
inconsequential 不合逻辑的，不合理的 *in (=not), con<com( =together) obsequial 葬礼仪式的 *ob( =to, intensive)
4.frag(=break)
fragile 易碎的 fragmentation 分裂
infringe 违反，侵害 *in( =in, against)
5.ple(=fill)
complement 补充物；补语 *com( =with)
plenipotent 有全权的 *pot(=powerful)
repletion 充满 *re(=again)
6.substantial [sub( =under) +st( =stand)站在下面]
adj. virtual; having physical existence; essential; solidly or strongly built or made;large; ample; considerable; well-to-do 实质的，本质上的；健壮的，结实的；大量的，丰富的，丰足的；富裕的
substantiate 证实；使实体化 substance 物质：本质；要旨；坚固；财产
substantive 独立的；实际的
举例： He promised me a substantial salary raise around the first of the yerar.
他答应我，年初左右会给我大幅度提升薪水。
7.sustain [sus<sub( =under) +
vt. keep from falling or sinking; keep up; maintain; suffer, undergo; support;
uphold-admit 支撑；维持；遭受、蒙受损失等；经历，承受：供养，维持（生命等）；确认；认可 sustenance 生计；食品，营养品；维持
举例： During the lean years, egg sales alone sustained our farm.
赶上灾年，我们只能靠卖鸡蛋来维持农场的生计。
8.subjugate [sub (=under) +jug (=bind, join)在下面捆]
vt. bring under control or subjection; conquer 使服从；使从属；征服
subjugation 从属；征服
举例： Rapists subjugate women not only physically but also emotionally.
强奸犯不仅从身体上而且从情绪上迫使女性屈从。
9.succumb [suc<sub( =under) +cumb( =lean．lie)向下屈身]
vt. to+sth give way to; yield to temptation, flattery, etc.; die 屈服，屈从于；死
举例： He succumbed to malaria after several long nights of chills and fevers.
经受了几夜的风寒和高烧，他最终死于疟疾。
10.supplant [sup<sub( =under,in place of) +plant( =plant)取代某物栽种]
vt. take the place of; take the place of someone, especially after getting him out of office 取代；把…排挤掉 supplanter 取而代之的人
举例： Lasers supplanted the use of scalpels for eye surgery decades ago.
激光替代了几十年前眼科手术中使用的解剖刀。
词根：
1.st(=stand)
unstable 不稳定的 *un (=not)
estate 阶级；地产；财产 *e<ex( =out)
obstacle 障碍（物） *ob( =in the way)
2.tain(=hold)
contain 包含 *con<com( =together)
maintain 维持 *main<man( =hand)
obtain 碍到，获得 *ob( =to, intensive)
3.
conjugation 结合，连接 *con<com( =together)
conjugal 夫妇间的；结婚的 *con<com( =together)
conjugal 婚姻；夫妻生活 *con<com (=together)
4.cumb(=lean,lie)
encumbor 妨碍 *en (=in)
incumbency 负担，义务；在职 *in( =on)
incubus 噩梦；心理负担 *in (=in)
5.plant(=plant)
implant 灌输 *im<in (=in)
transplant 移植 *trans( =over, across)
transplantation 移植 *trans(=over, across)