For physical thickness:
* Trwchus: This is the most common word for "thick" when referring to physical objects.
* Trwchus: This is the masculine form of the word for "thick".
* Trwch: This is the feminine form of the word for "thick".
For other meanings of "thick":
* Dwbl: This means "double" or "thick" in the sense of being layered or dense.
* Tyn: This means "tight" or "thick" in the sense of being compact or dense.
* Diffaith: This means "unfaithful" or "thick" in the sense of being slow to understand or stupid.
It's important to consider the context when choosing the appropriate word for "thick" in Welsh.