Used to state a negative consequence that will happen if the preceding condition is not met. Often at the beginning of a sentence.
Please hurry up. Otherwise, you'll be late.
Study harder. Or else you'll fail the exam.
Rare kanji spelling; not recommended for modern use.
Rare kanji spelling; not recommended for modern use.
Derived from 然も (samo, 'in that way') + 無い (nai, 'not') + と (conditional particle). The exact historical development is uncertain, but it functions as a fixed conjunction meaning 'if not so'.