Be- (A.S.), the most fertile of all English prefixes, is the weak form of by. The original meaning was 'about.' (1) It forms derivative verbs, with the sense of 'around,' 'on all sides,' 'in all directions,' as beblear=to blear all over, begirdle, bejumble, bepaste, besmudge; (2) it forms intensive verbs, with the sense of 'thoroughly,' 'soundly,' as bebreech=to breech soundly, bedaub, bewelcome; (3) it renders intransitive verbs transitive by adding a prepositional relation, as bechatter=to environ with chattering, begaze=to gaze at, besmile=to smile at, bespeak; (4) it forms transitive verbs of adjectives and substantives, as befoul=to affect with foulness, bedim=to make dim, bedew=to cover with dew, befriend.
Bis-, Bi-, Bin- (L.), twice, double, as biscuit, biennial, binocular; as ba- in balance. [Corr. of duis, ablative of duo, two.]
Cata-, Cath-, Cat- (Gr.), down, downwards, according to, thoroughly, as cataract, catholic, catechism. [Gr. kata.]
Circum-, Circu- (L.), round about, as circumscribe, circuit. [Properly accusative of circus, a circle. See Circle in Dict.]
Cis- (L.), on this side, as cisalpine.
Com-, Con-, Co- (L.), together, with, as connect, cohere, collect, correct, council. In curry, this prefix has been attached to O. Fr. roi, order; often intensive, as commotion; co-admire, co-enjoy, co-actor, co-believer. [Com- is the old form of L. cum, with; cog. with Gr. syn, Sans. sam. The root, originally signifying 'one,' is seen in L. sim-ul, together, Gr. ham-a, together, Eng. simple (which see in Dict.).]
Contra-, Contro-, Contr-, Counter- (L.), against, as contradict, controvert, contralto, counteract. [L. contra (whence Fr. contre), from Con-, and -tra, from root tar, to cross, seen also in trans.]
De- (L., or Fr.—L.), down, from, away, occurs in words derived either directly from L., as deduce; or through the Fr. from L., in which case De-, Di-, represents either (1) O. Fr. des- from L. dis-, asunder, not, as in defeat (O. Fr. des-fait), or (2) Fr.—L. de-, as describe [lit. 'write down'], decompose. This prefix de- is negative and oppositive in destroy, desuetude, deform, or intensive in declare, desolate, desiccate.
Demi- (Fr.—L.), half, as demigod, demiquaver. [Fr. demi—L. dimidium, half.]
Di- (Gr.), double, as dilemma, dialogue.