It comes from Latin and it means: plentiful, generous, copious, luxuriant, etc. It is an adjective because it goes next to a noun and characterizes the noun: 'There is an abundant (adjective) supply (noun characterised by "abundant") of cheap labour nowadays'.
It is describing something
'Abundant' is an adjective, which means it describes a noun or pronoun. It implies plentifulness or more than enough, enhancing the understanding of the noun it modifies. For example, in the phrase 'an abundant supply', 'abundant' describes the noun 'supply'.
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