Cancel the inner alarm. Big words don't make you sound smart. They make your stuff hard to read.
Don't say masticate. Say chew.
Don't say expectorate. Say spit.
Don't say pandiculate. Say yawn.
This is not about targeting an eighth-grade reading level, a myth born of arrogance. It's about capitalizing on our tendency to follow the course of least resistance. Even the stuffiest PhD is more likely to opt for an easy read over an impenetrable one.
A good copywriter disappears behind writing that brings to life the product or service for sale. Sounding credible can enhance that effect. But devices that draw attention to the writer ("Gee, this writer sure knows big words") steal the product's spotlight.