Complete the analogy: altus is to altissimē as grācilis is to?

The analogy is based on the formation of comparative and superlative degrees of adjectives in Latin. "Altus" is an adjective meaning "high," and "altissimē" is its superlative form, meaning "highest." Similarly, "grācilis" means "slender," and the correct corresponding superlative form is "grācillimē," which means "slenderest."

The superlative form in Latin is typically formed by adding the suffix "-issimus, -issima, -issimum" to the base of the adjective or modifying it with additional components, such as "grācillimē" that uses the superlative prefix to emphasize the meaning of "most slender." Understanding these grammatical structures is crucial for translating and manipulating Latin adjectives.

Therefore, the answer is correctly identified as "grācillimē," reflecting the superlative form that matches the construction seen with "altus" and "altissimē."