Prefix · direction · toward
Means "toward" or "near": adapt, advance, admit, adopt, advantage, advertise, advise.
Written by Bryan López, English teacher · Updated
Ad- comes from Latin and means "toward" or "near". Think of getting closer or adding to something: moving in the direction of another thing. It is the opposite of ab-, which moves away, and you will find it in lots of everyday words.
Ad- has a trick: the d changes to match the letter that comes next, because that is easier to say. That is why many words that start with ac-, af-, ap-, ar-, as- or at- have a hidden ad- inside. If you see a word with a double consonant near the start, ask yourself whether there is a disguised ad-. Twelve forms in all, and every one of them means "toward".
Assimilates to the following consonant, producing many surface forms:
Pronunciation: /æd/ (stressed) or /əd/ (unstressed). The double consonant in words like affect, arrive, assist, attract is the visible sign of ad- assimilation.
ad-/æd/ /əd/
Tap the button to hear how the prefix sounds. Each word in the table has its own audio.
When ad- precedes a consonant, the d assimilates to match it, creating a double: ad + fect → affect, ad + rive → arrive, ad + sist → assist, ad + tract → attract. Recognising this pattern explains both the meaning (always "toward something") and the spelling (the double consonant is the assimilation signal).
A trick to remember it
Picture walking toward something: ad- = toward. adapt, advance.
Exercise 1 · Form the word
Exercise 2 · Pick the right one
Which word hides assimilated ad- inside it?
The prefix ad- means "toward" or "near": adapt, advance, admit, adopt, advantage, advertise, advise.
The prefix ad- is pronounced /æd/ /əd/. For example, "adapt".
"apt" becomes "adapt". It is a typical example of the ad- prefix.
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