(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)
The Latin element ad carries the idea of "in the direction of" and combines with many Latin words and roots to make common English words.
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.
2. To send someone to work in a particular place or with a particular group of people.
3. To determine that someone or something has a particular quality, name, use, or category: "He was assigned a high employee rating based on his high attendance on the job."
4. To put a soldier or military unit under a particular command or assignment of duty.
5. To designate a value for a computer memory location corresponding to a named variable.
2. To wait on; minister to; to serve; such as, to serve as a doctor during an illness.
3. To accompany; to go with.
4. Etymology: "to direct one's mind or energies"; from Old French atendre, "to expect, to wait for, to pay attention"; from Latin attendere, "to give heed to"; literally, "to stretch toward"; from ad-, "to" + tendere, "to stretch".