The correct spelling of the phrase "is the mend" may seem confusing. However, the IPA phonetic transcription can help to make sense of it. The word "mend" is pronounced as /mɛnd/, with a short "e" sound. The extra "the" in the phrase is simply a matter of emphasis, indicating that something is truly in the process of being repaired. So, although the phrase may seem odd grammatically, its spelling is based on the standard pronunciation of the word "mend".
There is no commonly recognized phrase or idiom called "is the mend" in the English language. It is possible that you are referencing a lesser-known or obscure expression. However, based purely on the words used, we can provide a general dictionary definition for each:
"Is" is the third person singular present tense of the verb "to be." It is used to indicate something's existence, state, or identity, often equating or describing a subject with a specific quality or condition.
"The" is a definite article that specifies or identifies a noun as already known or previously mentioned.
"Mend" is a verb that means to repair, fix, or restore something that is broken, damaged, or in a state of disrepair. It typically refers to improving or rectifying the condition of an object, often through physical or mechanical means.
Combining these definitions, "is the mend" does not form a coherent phrase, idiom, or common expression in the English language. It is possible that you may be referring to an inaccurate or misunderstood phrase. It would be helpful to provide more context or details for a more accurate response.