un sweat (but it's pronounced 'sweet')
A hoodie (hooded sweat-shirt) is called "un sweat à capuche" in French.
Sudadera
a man's shirt is called 'une chemise' (fem.) in French.
a jumper (clothes) is called 'un pull' (masc.) or 'un sweat-shirt (masc.) in French
I would choose a shirt that says "buttercup"
un sweat rayé (sweat is pronounced sweet)
un beau T-shirt
a sweat shirt
sweat and its feminine
un chemisier
chemise grise
French just call it ... le T-shirt. The word is commonly used and has no french synonym. It is written T-shirt or tee-shirt. Either is acceptable. The word t-shirt was not gallicized upon entering the French language, and is a masculine noun.