词根：sid(sed, sit), sess(sid) = to sit 坐
词根sid来源于拉丁语的不定式词干 sidere,词根sess来自动名词词干，都意为to sit（坐）或to settle（安定）。sid为元音弱化后形成的词根。sid,sess属于一对同源异形根，反义词根有来自拉丁语的st,stat,stit,sist等。
同源词：
1. assiduous [一直坐着的as<ad(=to,intensive)+sid(=sit)]
adj.“constant or unwearied in application; diligent 刻苦的；勤奋的：He is assiduous in his study 他学习勤奋。
assiduity [as-; sid;-u-；-ity n.]n.刻苦；勤奋
2. preside [before前；sid= to sit 坐；-e- “to sit before others 坐在其他人前面”] v. sit in authority; act as chairman 主持；作会议主席：
to preside at a meeting 主持会议
presider n.（会议的）主席；主持者
presidium n．主席团；常务委员会
3. president v.主持，当权；-ent n．= person 人 →]
n.person chosen to preside over a nation. university or any other organization 总统；大学校长：会长：社长等
presidency n. 总统等的职位或任期
presidential adj. 总统（或校长等）的
4. reside [re-= back,down 回，下；sid = to sit or settle 坐，安放：-e → "to sit backward, to settle down 靠背安坐，安顿下来” →]
v. make one's home at a place 安家，居住：to reside in the city 在城市居住
resident n. 居民
residence n. 居住；住宅
5. subside [sub- = under,down下；sid= to sit or settle 坐，停留：-e →“to settle down 停在下面，停息”→]
v. ①sink down 下沉；沉降：The building subsides gradually. 这座房子逐渐下沉。
②fall into a state of quiet 平息：The wind has subsided 风停了。
subsidence n.下降；沉降；平息
6. dissident [dis-= apart 分开；sid= to sit 坐；-ent n. = person 人世间→ "person who sits apart from others 与别人分开坐的人”→]
n. person openly disagreeing with an opinion; dissenter 持异议者；反对者：political dissidents 持不同政见者
dissidence [dis-; sid; -ence n.] n. 异议；不一致
7. insidious [in- = in 内；sid= to sit 坐；-i-; -ous adj. = like 像……的_→ "like sitting in a hidden place，like setting an ambush 像坐在暗处的，像打埋伏的”→]
adj. ① intended to entrap 伺机为害的：insidious diseases 暗疾
②deceptive; treacherous 暗中为害的；阴险的：an insidious tempter 阴险的诱惑者
insidiousness n. 阴险；狡诈
8. session [sess= to sit 坐；-ion n. = the act or state 表行为或状态 →]
n. ① act of sitting 坐；就座
②sitting or time of sitting, as of a court or public body 开会；开庭；会期；开庭期：plenary session 全体会议
sessional adj. 开会的；开庭的
9. possess [pos(来自potis) = able 能……的；sess= to sit 坐→ "to be able to sit in a place 能坐在一个位置上”→]
v. ① inhabit or occupy 居住于；占据
② have or hold as property own 具有；占有：He possessed landed property 他拥有地产。
③ maintain or control 保持；控制：She was possessed by the desire to be rich 她被发财的欲望所支配。
possessor [possess; -or n.] n.占有人；所有人
possession [possess;-ion n.] n.占有；占有物；财产；领地
possessive [possess; -ive adj.] adj. 占有的 n.[语法]所有格
10. assess [as-(ad-) = to,at在；sess= to sit坐→“(judges in a court) to sit at or sit by（法官等在法庭）就座”→ "to judge or estimate 作判断，估计”→]
v. ①fix the value or profits of 对……进行估价：His property is assessed at one million dollars 他的财产估价为100万元。
② decide the amount of(a tax)征收（税款）：to assess a tax of ten pounds 征税10镑
assessment [assess; -ment n.] n.估价；评价
assessor [assess; -or n.] n. 估价财产的人；确定税款的人
assessable [assess; -able a.] adj.可估价的；可征税的
11. sedate [sed=sid坐+ate……的→坐着的,文静的]
adj.文静的
12. consider [con全部+sid坐+er→坐在一起→考虑到]
v.考虑,细想;体谅,顾及;认为,把…看作
13. supersede [从上往下坐下 super(=over)+ sed(=sit)]
vt. 代替；取代
supersession n.取代
Model AE-400x supersedes Model AE-200.模型AE-400X取代AE-200。
14. obsession [妨碍地坐着ob(=in the way)+sess(=sit)]
n.着迷；迷住
obsess v.妄想、固有观念等）萦绕心头，不停地困扰
obsessive adj. 使人着迷的
Eating is my hobby. Shopping is my obsession! 吃东西是我的兴趣，购物让我着迷！
15. sedan
n.箱式小客车（可容纳4人以上）；（17 - 18世纪的）轿子
sedan chair 轿子
16. sedimentary
adj.沉渣的，沉淀物的；由沉淀物生成的
sedimentary rocks 沉积岩（如粘板岩、石灰岩等）
17. sedulous
adj.坚忍不拔的；勤勉的，刻苦的；小心周到的
pay him sedulous attention 密切地关注他
18. saddle
n.马鞍； （自行车或摩托车的）车座； 鞍形架，鞍状物； （动物的）脊肉
vt.& vi.给（马）装鞍
vt.使承担
19. possess
v. 持有，拥有；控制；（恶魔、邪念等）缠住，迷住（某人） *pos (=powerful,able)
possess a large fortune 拥有大量财产
be possessed with/by devils 着魔的
be possessed with the idea that someone is persecuting him 着魔地认为有人在迫害他
be possessed by envy 内心充满嫉妒
20. possession
n. 所有；（pl.）所有物；财产 *pos(=powerful,able)
illegal possession of arms 非法持有武器
a man of great possessions 富翁
21. possessive
adj.所有的；所有权的；[语]所有格的；占有欲强的
possessive manner 极具占有欲的态度
possessive adjective/case/pronoun 所有格形容词/所有格/所有格代词
词根词缀：carpo-, carp- (cerp-)
【来源及含义】Latin: to pluck, to pick out, to gather, to select
【相关描述】The change of Latin "a" to "e" is due to the Latin phonetic law according to which in the unaccented and closed radical syllable of the second element of compounds, original "a" becomes "e".
【同源单词】Ancestors or Latin origins of words in English, cacoethes carpendi, caco, Carpe diem, Carpe noctem, Carpent tua poma nepotes
词根词缀：eosin-, eosino-
【来源及含义】Greek: daybreak, dawn, red of the dawn sky; primarily used in naming chemical compounds, especially pertaining to red stain or dye
【同源单词】eosin, eosinopenia, eosinotactic
词根词缀：hyper-, hyp-
【来源及含义】Greek: above, over; excessive; more than normal; abnormal excess [in medicine]; abnormally great or powerful sensation [in physical or pathological terms]; highest [in chemical compounds]
【相关词根词缀】 Related "above, over, beyond the normal, excessive" word units: epi-; super-, supra-, sur; ultra-, ult-. Inter-related cross references, directly or indirectly, involving word units meaning "more, plentiful, fullness, excessive, over flowing": copi-; exuber-; multi-; opulen-; ple-; pleio-; plethor-; poly-; super-; total-; ultra-; undu-.
【同源单词】acrohyperhidrosis, adenohypersthenia, alcoholemia, angiohypertonia, auditory hyperesthesia, bathyhyperesthesia
词根词缀：inter-, intero-
【来源及含义】Latin: between; among, mutually, together; on the inside, internal
【相关描述】Although abstracted from the many compounds in which it entered English, the form inter- was not generally considered a living prefix in English until the 1400s.
During the later period of Middle English many words borrowed in the Old and Middle French forms entre-, enter- began to be consciously respelled with Latin inter-; although vestiges of the older French borrowings are found in entertain and enterprise.
The living prefix inter- is now freely added to almost any element in English to create such formations with the meaning of "between" and "among". The words formed by intra- are closely related to this inter- prefix; in fact, they both apparently came from the same Latin source.
【相关词根词缀】 Related "together" units: com-; greg-; struct-. Cross references of word families related directly, or indirectly, to: "internal organs, entrails, inside": ent-; enter-; fistul-; incret-; intra-; splanchn-; viscer-.
【同源单词】ad interim, anterointernal, Caput inter nubila condit, electrical interference, electron compound, inter canem et lupum
词根词缀：-ium
【来源及含义】Greek: a suffix; scientific names; names of metallic elements; a part, lining, or enveloping tissue, region; little; representing a diminutive force
【相关描述】A suffix found on nouns borrowed from Latin; especially, derivatives of verbs (odium; tedium; colloquium; delirium); deverbal compounds with the initial element denoting the object of the verb (nasturtium); other types of compounds (equilibrium; millennium); and derivatives of personal nouns, often denoting the associated status or office (collegium; consortium; magisterium).
This ending of -ium also occurs in scientific terms on a Latin model; such as, in names of metallic elements (barium; titanium) and as a Latinization of Greek -ion (pericardium).
【同源单词】acute delirium, agrobacterium, aigialium, alluvium, andrium, anthium
词根词缀：methyl-, methy-
【来源及含义】Greek: a combining form occurring in the names of chemical compounds in which the methyl group is present; alcohol, wine
【相关描述】A "univalent hydrocarbon radical," 1844, from German methyl (1840) or French méthyle, back-formation from French méthylène, coined in French (1835) from Greek methy, "wine" + hyle, "wood". The word was introduced by Swedish chemist Jöns Jakob Berzelius (1779-1848).
【同源单词】hydroxymethyl, methanol, methylal, methylamine, methylate, methylene