Samasa Pada - සමාස පද - Compound Words.

Compound words are being more and more widely used. When they consist of only two words, they may have a hyphen or not. We write postcard, but post-bag and post office. If they consist of more than two words, these words are nearly always joined by hyphens.

A ten-year-old girl.

Forget-me-nots grow by streams.

He is a good-for-nothing fellow.

I saw three men-of-war in Colombo.

It was a never-to-be-forgotten day.

Is this an up-to-date atlas?

There is no limit to compound words. By the use of them we can turn one part of speech into another. There are no strict laws about them, and you should try to make them yourselves.