Final answer:
The word "altostratus" means a type of cloud that is high and stretches.
Step-by-step explanation:
The prefix "alto-" means "high" and the suffix "-stratus" refers to clouds, specifically a type of cloud. Altostratus clouds are mid-level clouds that are characterized by a uniform layer of gray or blue-gray clouds that often cover the entire sky. They usually indicate overcast conditions and can be associated with light rain or drizzle.
Therefore, the correct matching for the word "altostratus" would be:
Alto- high
-stratus stretch