IPA: /ˌkɒn.səˈveɪ.ʃən.ɪst/
KK: /kɒnˈsɜːrvəˌneɪʃənɪst/
A person who supports and works to protect the environment and natural resources.
As a conservationist, she dedicates her life to preserving endangered species.
Conservationist → It is formed from "conserve" (from Latin "conservare", meaning to keep together) and "-ist" (meaning a person who practices or is concerned with). A conservationist is a person who is concerned with keeping and protecting the environment and natural resources.
Think of someone who is 'keeping together' ('conserve') the environment — that's what a conservationist does.