词根词缀：ad-

【来源及含义】Latin: prefix; to, toward, a direction toward, addition to, near, at; and changes to: ac-, af-, ag-, al-, an-, ap-, aq-, ar-, as-, at- when ad- is combined with certain words that begin with the letters c, f, g, l, n, p, q, r, s, and t

【相关描述】The form ad- appears in this form before a vowel and before the consonants d, h, j, m, and v. It is simplified to a- before sc, sp and st.

Before c, f, g, l, n, p, q, r, s, and t; ad- is changed to ac-, af-, ag-, al-, an-, ap-, aq-, ar-, as-, and at-.

In other words, the d of ad usually changes into the same letter as the first letter of the following root or word when it is a consonant: ad-fix becomes affix, and ad-sign becomes assign; therefore, making a double consonant.

Another example includes: attract as with ad-tract (drawn towards); so it has a double t. On the other hand when ad- precedes a vowel, as with adapt, it is simply ad-apt, with one d. For the same reason, there is only one d in adore and adumbrate, because ad- has combined with orare and umbra each of which starts with a vowel.

So, remember: since these Latin words begin with vowels and not consonants, the d of ad does not double as shown in the previous examples.

【同源单词】a capite ad calcem, Ab ovo usque ad mala, Ab uno ad omnes, Abiit ad majores, abjure, accede

词根词缀：homo-, hom-, hum-

【来源及含义】Latin: human beings, mankind; literally, "man, men"; however, it now also includes, "woman, women" or all of humanity

【相关描述】This Latin homo- is related to humus, "earth" or "born" and so it is said to mean "earthly being" or "born of the earth" and it refers to all of humanity. Don't confuse this Latin homo- with the Greek homo- that means "same" or "equal".

【相关词根词缀】Links to other units that include the topic of "man", "mankind":
andro-; anthropo-; vir-.

【同源单词】ad hominem, Anno humanae salutis, Anno humanae salutis, argumentum ad hominem, Artes, Christo et humanitati