Estimation (noun)

1. The action of estimating or the process of being estimated.
2. An approximate calculation or judgment of the value, number, quantity, or extent of something.
3. A opinion or judgment about the worth, character, or ability of someone or something.

Origin:

Late middle english: from old french, or from latin estimatio(n-), from aestimare "value, estimate".

Examples:

1. The estimation of the cost of the project was based on past experiences and market trends.
2. Her estimation of the time needed for completion was overly optimistic.
3. The estimation of his worth was based on the value of his assets.
4. His estimation of her abilities was high, despite her lack of experience.
5. The estimation of the size of the crowd was difficult, as people were constantly moving.