Longman Dictionary of Contemporary English
economy class
noun
EXAMPLES FROM CORPUS
▪ Even at his best, he looks as if he has just stepped out of economy class after a flight from Bangkok.
▪ Flying economy class can kill you, and business class isn't much better.
▪ To his senior executives' chagrin, Mr McGovern always flies economy class and is proud of it.
Wikipedia
Economy class
__FORCETOC__ Economy class, also called coach class, steerage, or standard class, (colloquially: Cattle class), is the lowest travel class of seating in air travel, rail travel, and sometimes ferry or maritime travel. Historically, this travel class has been called tourist class on ocean liners and third class, or even fourth class, on railways. In some contexts or languages it is (half jokingly) referred to as "wood class" because seats and carriages in the cheapest class were literally made from wood in the 19th and early 20th century. Another common term (both in rail travel and aviation) is "coach class".