contraction

1.shortening： 类似于Jim is short for James
2.contraction：类似于 do not, don't
3.acronym：类似 Center Manager CM
4.Initialism ：类似于Monica.Wang MW
5. abbreviation：类似于Mister Mr.
你再自己体会一下就OK了

they've
contraction缩略词

abbreviation：缩略词

——指单词或片语缩短后的形式,主要用于在书面语中替代完整形式,如用 Mass. 替代 Massachusetts（马萨诸塞州）, 用 USA 替代 United States of Ameirica（美利坚合众国）, 用 RMB 替代 Renminbi（人民币）
.
contraction：缩约词/收缩词

——指通过省略或结合一个较长短语中的某些音素而形成的词,如 从 will not 收缩而来的 won't ,从 of the clock 收缩而来的 o'clock,诗歌中从 them 收缩而来的‘em

在图G中uv边缩减形成G'图,它的u,v两顶点合成一个顶点z,顶点z与G图中所有u,v的邻接点相邻

shrinkage 
noun1.the act or fact of shrinking.2.the amount or degree of shrinking.3.reduction or depreciation in quantity,value,etc.4.contraction of a fabric in finishing or washing.5.the difference between the original weight of livestock andthat after it has been prepared for marketing.
con·trac·tion 
noun1.an act or instance of contracting.2.the quality or state of being contracted.3.a shortened form of a word or group of words,with theomitted letters often replaced in written English by anapostrophe,as e'er for ever,isn't for is not,dep't fordepartment.4.Physiology .the change in a muscle by which it becomesthickened and shortened.5.a restriction or withdrawal,as of currency or of fundsavailable as call money.
这是我帮你查的字典.其实遇到这种问题,你可以直接查字典的哈.

contraction[英][kənˈtrækʃn] [美][kənˈtrækʃən]
生词本
简明释义
n.收缩,缩减；[语]缩略,略体,缩写；（开支等）缩减；（分娩时）子宫收缩
复数：contractions
以下结果由 金山词霸 提供
柯林斯高阶英汉词典 网络释义
1.N-COUNT（分娩时的）子宫收缩,宫缩When a woman who is about to give birth has contractions,she experiences a very strong,painful tightening of the muscles of her womb.
2.N-COUNT（词的）缩约形式A contraction is a shortened form of a word or words.
'It's' (with an apostrophe) should be used only as a contraction for 'it is'.
it's （带撇号）只能用作 it is 的缩约形式.
3.See also:contract；
以下结果由 金山词霸 提供
例句
A figure below 50 indicates a contraction in activity.
该指数低于50时表明经济活动出现收缩.