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Webster 1913 Edition

Adj.

Of considerable size or bulk.

“A sizable volume.”

Bp. Hurd.

Being of reasonable or suitable size;

as,

sizable

timber;

sizable

bulk

Arbuthnot.

Adj.

[from size.]

Of considerable bulk.

Being of reasonable of suitable size; as sizable timber.

sizable ‎(comparative more sizable, superlative most sizable)

(US, Canada) fairly large
He gave a sizable cash donation, sizable enough that the IRS wondered where all that money came from.
- 2015, Elizabeth Royte, Vultures Are Revolting. Here’s Why We Need to Save Them., National Geographic (December 2015)
  A vulture can wolf more than two pounds of meat in a minute; a sizable crowd can strip a zebra—nose to tail—in 30 minutes.

sizeable — see sizeable