Other forms: engineers; engineering; engineered
An engineer is someone who possesses the knowledge or expertise to create and implement plans or build machines. Even if you're not an engineer, when you engineer you make plans and solve problems.
An interesting part of the word engineer is the suffix -eer, which turns a word into one that means someone who does something indicated by the base it is affixed to — a mountaineer climbs mountains, an auctioneer presides at auctions, an engineer designs, coming from the Old French engin, which means "skill or cleverness." If you want to become an engineer, you'll have to study all kinds of mechanical systems, not just engines.