Language/English/Vocabulary/Alone,-lonely,-lonesome-and-lone

Alone, lonely, lonesome and lone 

Alone means ‘without others around’. Lonely (and informal American English lonesome) means 'alone and unhappy because of it’.  

Compare:

I like to be alone for short periods.

But after a few days I start getting lonely/lonesome. 

Alone can be emphasised by all. 

Example:

After her husband died, she was all alone. 

Alone is not used before a noun. Lone and solitary can be used instead; lone is rather literary. 

Example:

The only green thing was a lone/solitary pine tree.