second class is a noun and adverb meaning "not the highest rank in a classification". It carries 4 recorded senses.
not the highest rank in a classification
not the highest quality in a classification
a class of accommodations on a ship or train or plane that are less expensive than first class accommodations
by second class conveyance
“we traveled second class”
Definitions, synonyms and semantic relations for second class come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.