os

If: Os

Level 3

Os = if. The verb after it does not change: Os bydd hi'n braf, awn ni i'r traeth (If it's fine, we'll go to the beach).

How It Works

Future: os bydd. English says if it is fine, but Welsh says if it will be fine:

  • Os bydd hi'n braf, awn ni i'r traeth. — If it's fine, we'll go to the beach.
  • Bydda i'n hapus os byddwn ni'n ennill. — I'll be happy if we win.

Present: os + ydy, wyt, oes. After os, use the forms you use in questions, not mae:

  • Os ydy hi'n oer, arhosa i gartref. — If it's cold, I'll stay at home.
  • Os wyt ti eisiau, gallwn ni fynd yfory. — If you want, we can go tomorrow.
  • Os oes problem, ffonia fi. — If there's a problem, phone me.

In the South and in writing, ydy is often yw: os yw hi'n oer. See mae or ydy?

If not: os na. For a negative, use os na (os nad before a vowel) instead of ddim. Na brings mixed mutation: Os na fydd hi'n braf, arhoswn ni adre; os nad wyt ti'n siŵr.

No mutation. Os itself changes nothing, which is why the fixed phrase os gwelwch yn dda (please; literally if you see well) keeps its g.

Other kinds of if. For things that are not real (if I were rich), use taswn i. In everyday speech os also means whether: see a or os.

Examples (6)

  1. Os bydd hi'n braf, awn ni i'r traeth.

    If it's fine, we'll go to the beach.

    Bydd keeps its b after os.

  2. Os ydy hi'n oer, arhosa i gartref.

    If it's cold, I'll stay at home.

    After os, use ydy, not mae.

  3. Os wyt ti eisiau, gallwn ni fynd yfory.

    If you want, we can go tomorrow.

  4. Os oes problem, ffonia fi.

    If there's a problem, phone me.

    Os oes means if there is.

  5. Os na fydd hi'n braf, arhoswn ni adre.

    If it's not fine, we'll stay home.

    Os na replaces ddim, and bydd softens to fydd after na.

  6. Paned o de, os gwelwch yn dda.

    A cup of tea, please.

    Os gwelwch yn dda (please) literally means if you see well.

Common Mistakes

  • Using mae after os.

    Os mae hi'n oer, arhosa i gartref.
    Os ydy hi'n oer, arhosa i gartref.

    After os, use ydy (or yw), the same form you use in questions.

How It Connects

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

osLevel 3If: Os

Learn This First

Os takes ydy rather than mae, and often the future.

Words in This Pattern

os