We found one dictionary that defines the word line upon line:

General (1 matching dictionary)

1. Line upon Line: Dictionary of Phrase and Fable (1898)

▸ Words similar to line upon line ▸ Usage examples for line upon line ▸ Idioms related to line upon line ▸ Wikipedia articles (New!) ▸ Words that often appear near line upon line ▸ Rhymes of line upon line ▸ Invented words related to line upon line