1.
large size, large format, oversized
Something that is larger than the standard size. Used for books, paper, towels, and other items that come in size variations.
2.
large oval gold coin (historical)
A large oval-shaped gold coin used in feudal Japan, particularly during the Edo period. Often associated with wealth and treasure.
Usage
Sense 1 (large size) is common in everyday shopping and product descriptions.
Sense 2 (gold coin) refers to the historical currency. The pair 大判小判 (large and small gold coins) is well known from historical dramas and stories.
Common collocations
Watch out
The phrase for lavish generosity is 大盤振る舞い, from 椀飯振る舞い (a feast for guests). Writing it with 大判 is a common mistake, and it has nothing to do with gold coins.