The word(s) "solemn" appears 5 time(s) in 5 verse(s) in Quran in Muhammad Pickthal translation.

(1) And whoso disputeth with thee concerning him, after the knowledge which hath come unto thee, say (unto him): Come! We will summon our sons and your sons, and our women and your women, and ourselves and yourselves, then we will pray humbly (to our Lord) and (solemnly) invoke the curse of Allah upon those who lie.

(2) And they swear a solemn oath by Allah that if there come unto them a portent they will believe therein. Say; Portents are with Allah and (so is) that which telleth you that if such came unto them they would not believe.

(3) Will ye not fight a folk who broke their solemn pledges, and purposed to drive out the messenger and did attack you first? What! Fear ye them? Now Allah hath more right that ye should fear Him, if ye are believers

(4) They swear by Allah solemnly that, if thou order them, they will go forth. Say: Swear not; known obedience (is better). Lo! Allah is Informed of what ye do.

(5) And when We exacted a covenant from the prophets, and from thee (O Muhammad) and from Noah and Abraham and Moses and Jesus son of Mary. We took from them a solemn covenant;