【根】cuss＝to strike（打擊），to shake（搖動）

discuss
To speak with another or others about; talk over.
To examine or consider (a subject) in speech or writing
vt. 討論；論述，辯論

例句：
They discussed how to promote cooperation between the two countries.
他們討論如何促進兩國間的合作。
Mr. Wood refused to discuss the matter.
伍德先生拒絕討論這件事。

percussive
of or relating to percussion especially : operative or operated by striking
having powerful impact
adj. 沖擊的；叩診的，敲擊的

repercussion
An often indirect effect, influence, or result that is produced by an event or action.
A recoil, rebounding, or reciprocal motion after impact.
A reflection, especially of sound.
n. 反響；彈回；反射

concussion
A violent jarring; a shock. See Synonyms at collision.
An injury to an organ, especially the brain, produced by a violent blow and followed by a temporary or prolonged loss of function.
n. 沖擊；震蕩；腦震蕩

concuss
to injure by concussion
vt. 震動；恐嚇

例句：
He was caught by an avalanche and was seriously concussed.
他碰到雪崩，受到嚴重的腦震蕩。

abacus
A manual computing device consisting of a frame holding parallel rods strung with movable counters.
n. 算盤

詞源小故事

The adjective dusty, with its connotations of disuse and age, might seem to be an appropriate word to describe the abacus,since this counting device was used for solving arithmetical problems in the days before the advent of calculators and computers.Originally the abacus was, in fact, dusty.The source of our wordabacus, the Greek word abax, probably comes from Hebrew ’³b³q, “dust,” although the details of transmission are obscure.In postbiblical usage’³b³q meant “sand used as a writing surface.” The Greek wordabax has as one of its senses “a board sprinkled with sand or dust for drawing geometric diagrams.” This board is a relative of the abacus with movable counters strung on rods that is familiar to us.The first use of the wordabacus, recorded in Middle English in a work written before 1387, refers to a sand-board abacus, in this case, one used by the Arabs.The difference in form between the Middle English wordabacus and its Greek source abax is explained by the fact that Middle English actually borrowed Latin abacus, which came from the Greek genitive form (abakos ) of abax.

形容詞dusty 一詞帶有廢舊的隱含意義， 用這個詞來描述算盤似乎是合適的，因為在計算器和計算機發明以前，算盤是用來解決算術問題的計算工具。事實上算盤原本就很容易臟。abacus 一詞的希臘詞源abax可能源自希伯來語abaq,意為“灰塵”，但具體的演變過程已不是很清楚了。abaq 在《圣經》之后的用法中有“用以書寫的沙面”的意思。 希臘詞abax 有“在一木板上灑上沙子或塵土用以畫幾何圖形”之意。 這種木板就類似于我們所熟悉的裝有可移動算子的算盤。abacus 第一次被使用是在一本1387年以前用中古英語寫成的作品中， 指阿拉伯人使用的沙板算盤。中古英語的abacus 與其希臘詞源 abax 詞形上的區別是因為中古英語借用了拉丁文 abacus,而該拉丁文又是從希臘詞abax 的所有格形式 abakos 演變而來的