Adjective

(en adjective)

causing fear, dread, awe or admiration as a result of size, strength, or some other impressive quality; commanding respect; causing wonder or astonishment

difficult to defeat or overcome

* {{quote-news

, year=2012 , date=May 9 , author=John Percy , title=Birmingham City 2 Blackpool 2 (2-3 on agg): match report , work=the Telegraph citation , page= , passage=Holloway has unfinished business in the Premier League after relegation last year and he will make a swift return if he can overcome West Ham a week on Saturday. Sam Allardyce, the West Ham manager, will be acutely aware that when the stakes are high, Blackpool are simply formidable .}}

Adjective

(en adjective)

Manifesting, exercising, or favoring rigour; allowing no abatement or mitigation; scrupulously accurate; exact; strict; severe; relentless; as, a rigorous officer of justice; a rigorous execution of law; a rigorous definition or demonstration.

*{{quote-magazine, date=2013-08-03, volume=408, issue=8847, magazine=(The Economist)

, title= Boundary problems , passage=Economics is a messy discipline: too fluid to be a science, too rigorous to be an art. Perhaps it is fitting that economists’ most-used metric, gross domestic product (GDP), is a tangle too. GDP measures the total value of output in an economic territory. Its apparent simplicity explains why it is scrutinised down to tenths of a percentage point every month.}}

Severe; intense; inclement; as, a rigorous winter.

Violent.