Tetrahedron.
A triangular based pyramid would fit the given description
A 3D shape with one base and three faces can only have triangular faces.
It is a pyramid
Triangular based pyramid
If you are thinking of a solid object then it is a PYRAMID. NB Do NOT confuse with a TETRAHEDRON. This is a triangular base with three triangular faces.
pyramid
Pyramid
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pentagonal pyramid
Pyramid
A Triangular Pyramid, 3 faces, 1 base.
A three sided pyramid.