Ideal can be used as both a noun and an adjective in English.
As a noun, it means:
1. A standard of perfection or excellence
2. A conception of something in its most perfect form
3. A person or thing regarded as perfect
As an adjective, it means:
1. Satisfying one's conception of what is perfect
2. Existing only in the imagination
3. Representing an abstract or hypothetical optimum