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Isnot
Executive summary
The phrase “is not” is an ordinary English negation—used to make verbs, adjectives or clauses negative—or appears contracted as “isn’t” in speech and writing [1] [2]. Major dictionaries define “not” as a function word expressing negation, denial or prohibition and “isn’t” as the common contraction of “is not” [1] [3].
1. What “is not” and “not” mean in plain English
Grammarians treat not as a function word that forms negation: it turns affirmative verbs, auxiliaries and modals into negatives (for example, “is not,” “does not,” “will not”) and can negate adjectives or clauses; Merriam‑Webster and Cambridge both define not this way [1] [4]. Dictionaries emphasize that “not” signals refusal, denial or the opposite of a preceding idea—its core role is syntactic and logical rather than emotive [5] [6].
2. The contracted form: “isn’t” and usage notes
The contraction isn’t is the usual spoken or informal written form of “is not”; style guides and dictionary entries present it as equivalent in meaning, though contractions are less common in formal prose [7] [3]. Cambridge, Collins and Britannica list examples like “He isn’t coming until tomorrow” to show normal usage and pronunciation notes, including dialectal variants [2] [7] [8].
3. Grammar and common pitfalls: double negatives and scope
Resources warn about double negatives: using “not” with other negating words can change or cancel meaning (e.g., “I don’t know nothing” can be interpreted as affirmative in some dialects), so writers must attend to negation scope to avoid ambiguity [9]. Dictionaries such as Vocabulary.com and The Free Dictionary discuss how “not” interacts with other elements in a sentence and how contractions are often attached to auxiliary verbs [9] [6].
4. Differences between “no” and “not” — when to use each
“No” and “not” both express negation but serve different grammatical roles: “no” more often functions as a determiner or exclamation (“no money”, “No!”), while “not” modifies verbs, adjectives or whole clauses (“is not ready”, “not happy”)—a distinction emphasized in usage guides like Grammarly [10]. Choosing the correct form depends on the grammatical slot you need to negate.
5. Etymology and lexical entries: what dictionaries record
Dictionary entries collected here (Merriam‑Webster, Cambridge, Collins, Britannica, YourDictionary) consistently record “not” as a central negation word and document “is not” / “isn’t” as the negative form of “to be.” Merriam‑Webster traces “isn’t” historically and lists dialectal pronunciations; other dictionaries add example sentences and usage notes [11] [3] [7] [8].
6. Practical takeaways for writers and speakers
If you need formal tone, prefer “is not”; in informal speech or dialogue, “isn’t” is natural and common [7] [2]. Watch for double negatives and the difference between negating a noun phrase (use “no”) versus negating a verb/clause (use “not”) to avoid accidental affirmation or ambiguity [10] [9].
Limitations and unresolved points
Available sources do not mention any controversial or alternative technical senses of “is not” beyond standard negation and contraction uses; they also do not discuss regional pragmatic connotations beyond a few pronunciation notes [7] [3]. If you want research on sociolinguistic attitudes toward contractions or cross‑linguistic negation patterns, that topic is not covered in the provided material.