Example: He is a _ type of person
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Your question suggests someone susceptible to influence. But I'm not sure there is a single word to describe everything you want to convey, and context might be very important. I know that often people associate the sign Gemini with the traits you mention and "Geminian" is a word in the Oxford-American dictionary. However, it would sound stilted or arrogant in general use, and would very likely confuse your reader. – senortim Jul 16 '20 at 20:16
3 Answers
I prefer impressionable, as suggested by @KarimTabet, but I will add gullible and credulous to the possibilities he suggested. From Lexico:
gullible: Easily persuaded to believe something; credulous.
credulous: Having or showing too great a readiness to believe things.
"Someone whose personality or character changes a lot and get [sic] more affected than others by company or influential people" is more impressionable, gullible**, or credulous** than others.
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The person's personality would be described as malleable:
[Merriam-Webster]
2 a : capable of being altered or controlled by outside forces or influences
Using it with the example sentence:
He is a malleable type of person.
Or, more naturally:
He is weak-willed, and has a malleable personality that is easily influenced and changed by others.
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