The expression "not half" is a colloquialism commonly used in British English to intensify a negative statement. It is pronounced /nɒt hɑːf/ phonetically. In terms of spelling, the word 'not' is spelled normally, however, the word 'half' is spelled using the letters 'h', 'a', 'l', 'f', without any reference to a silent 'l' that we would typically expect in English. This can make the word appear to be misspelled to those unfamiliar with the phrase.
"Not half" is an idiomatic expression used to emphasize or intensify the degree of something. This phrase is commonly used in informal speech to convey a strong emphasis or affirmation of a certain quality or characteristic. It is often employed in British English, though its usage can be found in other varieties of English as well.
The phrase "not half" can be understood as the negative form of the expression "half," which typically represents a moderate or incomplete amount or intensity. When "not half" is used, it suggests that the degree or quality being referred to is not moderate or incomplete, but rather substantial, considerable, or even exceptional. It denotes a sense of wholeheartedness or fullness in whatever is being described, emphasizing that the degree or extent is far greater than anticipated or expected.
For instance, if someone were to exclaim, "That performance was not half bad!" they are expressing that the performance was actually quite good, even exceptional, contrary to initial expectations. Similarly, if someone were to say, "This cake is not half delicious," it means that the cake is exceptionally tasty, surpassing moderate satisfaction. Therefore, the phrase "not half" is a means of greatly amplifying the quality or degree of something, highlighting its remarkable or outstanding nature.
The phrase "not half" originated in the mid-19th century in British English. It is derived from an earlier expression, "not half bad", which was used to mean "better than expected" or "quite good". Over time, the word "bad" was dropped, and "not half" itself came to be used as an emphatic phrase to indicate that something was exceptionally good or impressive. The exact etymology beyond this point is unclear, but it is believed to have evolved from slang and colloquial usage.