Sizeable means fairly large. A sizeable crowd, a sizeable sum, sizeable losses.
It is deliberately vague — sizeable says large enough to matter without saying how large, which is why it appears in reporting when the writer does not have a number. The spelling sizable without the e is also correct and commoner in America.
1adjectivesizeableFairly large.
“She inherited a sizeable sum from her aunt and used it to buy a flat.”
sizeable is a quality of size.
Also accepted in games: sizable
sizable comes from size + -able.
Etymology from Wiktionary, CC BY-SA