• 以上いじょう — more than / above
• 以外いがい — except for
• 以来いらい — since
• 以下いか — less than / below
• 以前いぜん — before
• 所以ゆえん — for that reason

以 originally showed a pictograph of a person (人) followed by another symbol suggesting motion or action. It often expresses direction, means, or cause in compound words, and is common in formal language or writing.