petit bourgeois; petty bourgeois
Refers to the lower middle class, especially small business owners and shopkeepers, often with a nuance of conventional or narrow-minded values. Compare プチブルジョア, a more colloquial abbreviation.
See also: プチブルジョア
He comes from a petit bourgeois background; his parents ran a small shop.
I can't break free from a petty bourgeois way of thinking.