明明後日

Etymology 1
Compound of.

The initial shi element is uncertain. Speculatively, this might be related to, or a shift from, intensifying prefix found in some adjectives, such as.

First cited to a text from 1275.

Noun

 * 1)   three days from today, two days after tomorrow
 * 2)  four days from today
 * 1)  four days from today

Usage notes
This term and share a roughly complementary distribution between eastern and western Japan, wherein the terms alternate between meaning "three days from today" and "four days from today". Tokyo follows the Western Japan usage.

Etymology 2
Compound of.

First cited to the  of 1603.

Noun

 * 1)  two days after tomorrow, three days hence