What is the meaning of Nay?

Introducing a statement, without direct negation.

Or rather, or should I say; moreover (introducing a stronger and more appropriate expression than the preceding one).

A vote against.

A person who voted against.

Nary; not any

Clipping of nanay.

that is today, or happening today

now, the present, as opposed to xưa (“long ago; the past”) and mai (“later in the future”)

Clipping of hôm nay (“today”)

Clipping of bữa nay (“today”)

Source: wiktionary.org

See also