Here are some options:
For small things:
* Bach: This is the most common and versatile word for "little". It can be used for both masculine and feminine objects.
* Bychan: This is another common word for "little", often used for things that are physically small.
For people:
* Bach: This can be used for children, but it is generally considered more polite to use brawd bach (little brother) or chwaer fach (little sister) when talking to children.
* Bychan: This is less common for people, but can be used for very young children.
For other contexts:
* Ychydig: This is used for small amounts or quantities.
* Llai: This means "less" or "smaller".
Example sentences:
* Mae gen i frawd bach. (I have a little brother.)
* Mae'r tŷ yn fach iawn. (The house is very small.)
* Rwy'n eisiau ychydig o siwgr. (I want a little bit of sugar.)
The best word to use will depend on the specific situation. If you are unsure, it's always best to err on the side of caution and use a more general term like "bach".