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)

Able to be hammered into thin sheets; capable of being extended or shaped by beating with a hammer, or by the pressure of rollers.

(metaphorical ) Flexible, liable to change.

My opinion on the subject is malleable .

(cryptography, of an algorithm) in which an adversary can alter a ciphertext such that it decrypts to a related plaintext