an- / di- / dad-

Negative Prefixes: An-, Di-, Dad-

Level 5

teg (fair) → annheg (unfair); gwaith (work) → di-waith (unemployed); gwneud (do) → dadwneud (undo). Each prefix changes the first letter of the word after it.

How It Works

An- (not, un-). An- is the most common "not" prefix. It changes the next sound:

  • p, t, c and d take nasal mutation: posibl → amhosibl (impossible), teg → annheg (unfair), cyfforddus → anghyfforddus (uncomfortable), cofio → anghofio (forget)
  • b, g and m take soft mutation: bodlon → anfodlon (dissatisfied), mantais → anfantais (disadvantage), gwybodus → anwybodus (ignorant)
  • vowels, h and s stay: arferol → anarferol (unusual), hapus → anhapus (unhappy), sicr → ansicr (uncertain)

The spelling adjusts too: an- becomes am- before mh (amhosibl). Before ll, rh and gl the prefix is af-: aflwyddiannus (unsuccessful), afresymol (unreasonable). See Nasal Mutation.

Di- (without, -less). Di- is usually added to a noun and means "without". It causes soft mutation: gwaith → di-waith (unemployed), mwg → di-fwg (smoke-free), diwedd → diddiwedd (endless), gobaith → diobaith (hopeless). Some of these words have a hyphen and some do not, so check each one in a dictionary.

Dad- (un-, undo). Dad- reverses an action and causes soft mutation: gwneud → dadwneud (undo), pacio → dadbacio (unpack), llwytho → dadlwytho (unload), rhewi → dadrewi (defrost).

Learn the whole word. These changes are part of the word's spelling. The new word can then mutate again at its own start, like any other word: Mae e'n ddi-waith, with d softened after yn.

Examples (6)

  1. Mae hynny'n annheg!

    That's unfair!

    An- + teg: t takes nasal mutation, giving annheg.

  2. Ro'n i'n teimlo'n anghyfforddus.

    I felt uncomfortable.

  3. Mae'n amhosibl!

    It's impossible!

    An- + posibl gives amhosibl.

  4. Mae e'n ddi-waith ers mis Mai.

    He's been unemployed since May.

    Di- softens gwaith to waith; then yn softens di- to ddi-.

  5. Dw i newydd ddadbacio'r car.

    I've just unpacked the car.

    Dad- + pacio gives dadbacio, which softens again after newydd.

  6. Pwyswch yma i ddadwneud y newid.

    Press here to undo the change.

Common Mistakes

  • Adding an- without the nasal mutation.

    Mae hynny'n anteg.
    Mae hynny'n annheg.

    An- causes nasal mutation of t, so an + teg gives annheg.

  • Adding di- without the soft mutation.

    Mae e'n ddi-gwaith.
    Mae e'n ddi-waith.

    Di- causes soft mutation, so gwaith loses its g: di-waith.

How It Connects

Tap a pattern to see what it builds on and what it leads to.

an- / di- / dad-Level 5Negative Prefixes: An-, Di-, Dad-

Learn This First

Negative prefixes mutate the word they attach to.

Words in This Pattern

an-di-dad-