Real Dictionary

angel
countable noun: Angels are spiritual beings that some people believe are God's servants in heaven.
countable noun: If you describe someone as an angel, you mean that they seem to be very kind and good.
countable noun: You can call someone you like very much an angel in order to show affection, especially when they have been kind to you or done you a favour.

angel in American English
a messenger of God
noun: a male or female given name
noun: one of a class of spiritual beings; a celestial attendant of God. In medieval angelology, angels constituted the lowest of the nine celestial orders (seraphim, cherubim, thrones, dominations or dominions, virtues, powers, principalities or princedoms, arc
transitive verb: to provide financial backing for

angel in British English
noun: one of a class of spiritual beings attendant upon God. In medieval angelology they are divided by rank into nine orders: seraphim, cherubim, thrones, dominations (or dominions), virtues, powers, principalities (or princedoms), archangels, and angels

angel in Finance
noun: An angel is an investor who uses their own funds to provide capital for a startup.