词根：-rat-

【词根含义】：计算,思考

【词根来源】：来源于拉丁语动词reor, reri, ratus, sum(计算,思考)。

【同源单词】：irrational, overrate, rate, ratify, rating

前缀：il-, in-, ir-, im-

【词根含义】：不,无,非;入,向内

【词根来源】：(il-用于l前;im-用于b, m, p前;ir-用于r前;in-用于其它情况)   来源于拉丁语in。

【同源单词】：illegal, illegality, illegitimate, illiterate, illogical

词根词缀：-able

【来源及含义】Latin: a suffix; expressing capacity, fitness to do that which can be handled or managed, suitable skills to accomplish something; capable of being done, something which can be finished, etc.

【相关描述】A suffix that forms adjectives. The suffix -ible has related meanings; expressing ability, capacity, fitness; capable of, fit for, able to be done, can be done, inclined to, tending to, given to.

This list is only a small sample of the thousands of -able words that exist in English.

【同源单词】abdicable, -able, abolishable, abominable, abradable, acceptable

词根词缀：in-1

【来源及含义】Latin: no, not [ig-, il-, im-, ir-]

【相关描述】This in-, "not", becomes i- before gn, as with "ignore"; il- before l, as with illiterate; im- before b, m; and p, as with imbalance, immiscible, impecunious; and ir- before r, as with irrefragable.

Don't confuse this Latin prefix, in-¹, meaning "not", with another Latin prefix in-² meaning "in, into, within, inside, on, toward" or with the prefix for English-origin words in-³ meaning "in, into; within".

【同源单词】ignorance, illiterate, imbalance, immaculate, immature, immovable

词根词缀：ratio-, reason-

【来源及含义】Latin: reckoning, to reckon; calculating, calculation; understanding; thinking

【同源单词】arraign, arraigner, arraignment, derationalize, irrational, irrationalism