In English, blah is a wor that is sometimes used as an expression for words or feelings where the specifics are not considered important to the speaker or writer for emotions.It is not often seen in formal writing, except when transcribing speech. It differs from a speech disfluency such as "um" or "er" in that blah is a word used deliberately to represent other words, rather than as an accidental or temporary interjection into speech. Blah is also used when the speaker cannot say what was intended. "Blah" is also mimed behind people's backs to suggest that they talk too much or that they talk about useless topics for no reason. The word "Blah" can also be used in a mocking or sarcastic tone.