Here's what rhymes with lengthiest.
Words that almost rhyme with lengthiest
wealthiest airiest edgiest leggiest heaviest deadliest recreant veriest lariat pettiest emptiest wariest hairiest fleshiest heftiest dressiest stealthiest fleshliest peppiest peskiest testiest preppiest tetchiest zestiest teariest variant chariot prescient friendliest scariest sexiest sketchiest cheviot cleanliest smelliest sweatiest stretchiest homeliest comeliest cerement invariant unfriendliest uncleanliest proletariat secretariat commissariat