Final answer:
The underline word in the sentence is an adjective. Adjectives describe or modify nouns.
Step-by-step explanation:
The underline word in the sentence is adjective. An adjective is a word that describes or modifies a noun. In this case, the word 'shallow' describes the lake. Adjectives answer questions like 'What kind?', 'Which one?', or 'How many?'. In the sentence 'The shallow lake was full of salmon and other fish', 'shallow' describes the noun 'lake'.
Learn more about The part of speech in the sentence