1 material, considerable, significant, great, worthwhile, consequential, ample, goodly, respectable, abundant, generous, big, large, sizeable, major, Colloq tidy, healthy:
We understand that he made a substantial payment to keep his name out of the papers.
2 strong, solid, well-built, durable, sound, stout, sturdy; big, large, massive, huge, sizeable, impressive, vast; numerous, numberless:
A substantial mausoleum was constructed for his family. A substantial crowd had gathered.
3 well-founded, sound, weighty, solid, well-established, telling, good, valid, actual:
Many economists produced substantial arguments in favour of another cut in interest rates.
4 wealthy, well-to-do, rich, affluent, prosperous, profitable, successful; landed, propertied:
The Trevelyan Ironworks is a substantial business, and Mr Trevelyan is one of our more substantial businessmen.