{i} sequence of words that are difficult to pronounce rapidly and correctly due to its irregular sequence of sounds (for example: "Five fine Florida florists fried fresh flat flounder fish fillet")
an expression that is difficult to articulate clearly; "`rubber baby buggy bumper' is a tongue twister
A phrase that is deliberately designed to be difficult to say correctly, usually because of varying combinations of similar phonemes
“Red lorry, yellow lorry” and “Peter Piper picked a peck of pickled peppers” are well-known tongue-twisters.
A tongue-twister is a sentence or expression which is very difficult to say properly, especially when you try to say it quickly. An example of a tongue-twister is `Red leather, yellow leather'