Hi there 
what are the differences of meaning between
Painting - picture - square ???
If I shoud describe such object in my room, I mean one enclosed in a frame, which of the above mentioned should I use?
Thanks!
Alex
We can safely rule out ‘square’ as this is just a shape.
A painting is a picture made using paint, like oil or watercolours.
A picture can be a painting, a drawing, a print, a photograph, etc.
Some languages use their word for “square” to mean picture, but English never does this. If you say “square” and want to indicate a picture, no one will understand you. As Conchita said, square is just a shape in English.
If you have one in your room, you can either call it a picture, or you can use the name of the actual medium – painting, photo, etching, drawing, etc.