There are a total of 42 8-letter words containing 'rial', and the number may vary in different dictionaries. You can specify the dictionary and order.

• aerially ₁₂
• aquarial ₁₉
• armorial ₁₂
• arterial ₉
• biserial ₁₂
• decrials ₁₃
• etherial ₁₁
• filarial ₁₃
• fimbrial ₁₈
• gharials ₁₃
• imperial ₁₅
• malarial ₁₃
• manorial ₁₃
• manurial ₁₄
• material ₁₂
• memorial ₁₅
• mistrial ₁₂
• notarial ₁₀
• patrials ₁₂
• pretrial ₁₂
• puparial ₁₆
• rasorial ₉
• reburial ₁₃
• retrials ₉
• serially ₁₂
• tenurial ₁₁
• trialing ₁₂
• trialist ₉
• trialled ₁₁
• tutorial ₁₀
• vicarial ₁₆
• vizirial ₂₂
• conarial ₁₀
• motorial ₁₀
• pairials ₁₀
• riparial ₁₀
• sororial ₈
• soterial ₈
• squarial ₁₇
• sutorial ₈
• trialism ₁₀
• triality ₁₁

There are 42 8-letter words containing rial in the well-known word game dictionary, 29 in the Scrabble US (US/Canada/Thailand - TWL/NWL) dictionary, and 41 in the Scrabble UK (International - SOWPODS/CSW) dictionary, and 32 in the Words with Friends (WWF) dictionary.