〜さえ／でさえ
Even (an extreme example)machine translation
FormationNoun (+ particle) + さえ／でさえ; the particles が・を are usually replaced entirely by さえ
さえ gives an EXTREME example and lets the listener infer the rest: そんなことは子供でさえ知っている (even children know that) — with the implication that adults obviously know it. With subjects, use でさえ; in the position of が・を, さえ replaces the particle entirely: 水さえ飲めない (can't even drink water).
さえ is much stronger than も. 子供も知っている merely adds "children know it too"; 子供でさえ知っている is striking: "even children know it, mind you." Because of this "to that extent" nuance, さえ appears very often in negative sentences and complaints: 忙しくて日曜日でさえ休めない.
Don't confuse it with the pattern 〜さえ〜ば: when a ば-form follows, さえ changes meaning entirely to "as long as… that's enough." A quick tip: if there is a ば in the following clause, it's the minimum-condition pattern; with no ば, さえ means "even."
Examples
忙しくて、日曜日でさえ休めません。
I'm so busy I can't even take Sundays off.
そんなことは子供でさえ知っています。
Even children know that.
彼は疲れていて、水を飲むことさえできませんでした。
He was so exhausted he couldn't even drink water.