The old word for "yourself" when speaking to one person — the partner of "thou" and "thy". Like them, it belongs to the Bible, old prayers, hymns, and Shakespeare, not to modern speech. It does the same two jobs "yourself" does today. First, the reflexive job, where the action comes back on the person: "Love thy neighbour as thyself." Second, the emphasis job, where it is added just to stress who you mean: "Thou thyself hast said it." A few famous lines keep it alive for people who have never read any old English: "Know thyself" (the old Greek motto, usually given in English this way) and "Physician, heal thyself." You may also meet the older spelling "thyselfe". Modern writers reach for it when they want an ancient or solemn tone, and fantasy games and jokey signs use it the same way — often mixing it up with "yourself" halfway through a sentence, which real old English would never do.