ad-

(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.

adoption
1. The act of accepting with approval or a favorable reception.
2. A term for a situation in which adult animals take over the care of young who are not their own offspring.
adoral
1. Situated toward or near the mouth.
2. Directed toward the mouth.
adore
1. To love someone intensely.
2. To like something or someone very much.
3. To regard with deep, often rapturous love.
4. To worship God, a god, or a spirit.
5. Etymology: from Old French aourer, "to adore, to worship"; from Latin adorare, "to speak to, to entreat, to beseech, to ask in prayer, to worship"; from ad-, "to" and orare, "to speak, to pray".
adorn
1. To add decoration or ornamentation to something.
2. To add to the beauty or glory of something or someone.
adrenal
1. Near or upon the kidney; denoting the suprarenal (adrenal) gland.
2. A suprarenal gland or separate tissue or product thereof.
adsorb, adsorbable, adsorbability
To take up and to hold another substance on the surface in order to carry on the process of adsorption.
adsorbate
Something which is absorbed; such as, material gathered on a surface by adsorption.
adsorbent
1. A material that can hold or condense molecules of another substance on its surface by adsorption.
2. Relating to or capable of adsorption.
adsorption
The taking up of the molecules from a gas or liquid on the surface of another substance; distinguished from adsorption, a process where one substance actually penetrates into the inner structure of the other.
adtital
Relating to an organism living immediately below low-tide levels.
adulterer
Someone who commits adultery or fornication (sexual intercourse between partners who are not married to each other).

The word fornication had a less than socially respectable beginning suitable to what has long been the low moral status of the act to which it refers. From Old French fornication, from Late Latin fornicationem (fornicatio), from fornicari "fornicate", from Latin fornix, "brothel"; originally "arch, vaulted chamber"; from fornus "oven of arched or domed shape".

Roman prostitutes commonly solicited customers from under the arches of certain buildings. So, fornication means, "voluntary sex between an unmarried man and an unmarried woman"; extended in the Bible as adultery.

adumbration
The fact of being darkened or overshadowed.
advance
1. To move, or to move someone or something, forward in position.
2. To put something forward; such as, a proposal.
3. To supply something or part of something; especially, money, before it is due.
4. To rise, or to make or help someone rise, in rank or position.
6. To make something happen earlier than originally expected.
advantage
1 A superior or favorable position in relation to someone or something: "He was hoping to gain an advantage in the negotiations with the company."
2. A circumstance or factor that places someone in a favorable position in relation to another person or to other people.
advection
1. The transfer of a property of the atmosphere; such as, heat, cold, or humidity, by the horizontal movement of an air mass: "Today's temperatures were higher due to the advection of warm air into the region."
2. The rate of change of an atmospheric property caused by the horizontal movement of air.
3. The horizontal movement of water, as in an ocean current.