prophecy and prophesy - the difference
 
A prophecy is knowledge of the future (from a divine source).
To prophesy means to predict the future (with divine inspiration).
 

    Grammar Checker

Prophecy

The word prophecy is a noun. (The last syllable of prophecy is pronounced sea.) A prophecy is knowledge of the future - usually said to have come from a divine source.

Examples:

On the second day of the course, we will study the prophecies of Nostradamus.

The prophet has revealed his latest prophecy in which three cities are razed to the
ground.

Prophesy

The word prophesy is a verb. (The last syllable of prophesy is pronounced sigh.) To prophesy means to predict the future - usually with divine inspiration.

Examples:

He prophesies a great war between East and West.

He prophesied that a flood would cover the Earth.
 
NOT PROPHESIZE OR PROPHESISE 

I prophesy
You prophesy
He prophesies
We prophesy
You prophesy
They prophesy

There is no such word as prophesize or prophesise. This is most commonly seen as:

He prophesizes
(should be prophesies)
 

See also:

What are nouns?
What are verbs?
List of easily confused words