sequacious, adjective
I suppose my favorite definition is from Merriam-Webster:
2 : Intellectually servile.
And from the Oxford Dictionary (no longer available online):
Of a person: Lacking independence or originality of thought.
Finally, the definitive definition from the Oxford English Dictionary:
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a. Of a free agent or his attributes: Given to following another or others, especially a leader.
b. Given to slavish or unreasoning following of others (especially in matters of thought or opinion).