SAI
v. C2 Proficiency US //ˈɛˈseɪˈaɪ// sai
v. to know something. This is a very old-fashioned way of speaking that you might see in old books or poems.
v. the archaic third-person singular present of 'wit', meaning to know. Used in modern English only as a deliberate archaism or in historical literary contexts.
God sai what is in your heart.
In the old manuscript, the knight claims that only the king sai the true location of the treasure.
The poet employs archaic forms like 'sai' to evoke a sense of medieval mysticism, though such terms have long since vanished from standard spoken English.
Usage
An archaic verb form; in modern contexts, it is almost exclusively found in historical fiction or religious texts.