The word modish is a combination of the French mode meaning "fashion" and the suffix -ish meaning "very common."  When something is modish, it's all the rage. A swanky restaurant where it's hard to get a table or a boutique selling the newest designer labels are considered modish, or in vogue. 

The earliest known use of the word modish is in the mid 1600s.  The OED's earliest evidence for modish is from 1652, in the writing of Edward Benlowes, poet.  

Examples of "modish" in a sentence: 
"He wore a modish gray suit and hat."
"From furs to chic trench coats, this season is all about bundling up with a modish twist."
"The modish cafe has bounties of greenery inside and out."
"But that modish phrase does not quite capture what is going on." 
"The contemporary art lover prefers modish pieces over traditional pieces from the past." 
"Max wanted his hair cut into a modish mohawk instead of the outdated style his dad always made him get." 
"Grandmother knows nothing about fashion trends, so she thinks I should replace my modish skirts with outdated clothes from her day."