IPA: /ˈmɑːrkɪtər/
KK: /ˈmɑrkɪtər/
A person or company that promotes or sells products or services to customers.
The marketer created a new advertising campaign to attract more customers.
Marketer → It is formed from "mark" (from Old English *mearc*, meaning boundary or sign) and "-er" (meaning a person who). A marketer is a person who creates signs or boundaries in the context of promoting products or services.
Think of someone who creates 'signs' ('mark') to promote or sell something — that's what a marketer does.
No commonly confused words.