Antonym of "nonsensical"
- You might get some insight from this...I am suggesting that "nonsensical" is an unpaired word like "unwittingly".
- Possible antonyms:
- sensible
- coherent
- logical
- intelligible
- meaningful
"Sensical" is in fact a valid antonym for nonsense. It is a word, and you can use it. It is in the Oxford English Dictionary. It's use is traced back to 1797. It is equated to "sensible." My version is the 23rd US Printing, 1984 the Micrograph edition. You may find the word on page 2,728.
Sensical has not yet become an "official" word in the English language, which would be why you can't use it. Nonsense is a word, therefore nonsensical can used to describe something of nonsense. However, sense has different meanings and doesn't have an adjective for something of sense. English language speakers generally do not use sense as an antonym of nonsense. Possible antonyms of nonsensical include logical, rational, or reasonable.
In fields like logic, philosophy, or linguistics, where you want word pairings like sense/nonsense to be very precise, the term 'sensical' actually is in use, because 'sensible' is already used to mean 'pertaining to the senses' and having such ambiguity isn't really permissible in such context. Thus in ordinary writing, or writing in other fields, it probably ought to be avoided because it strikes one as awkward, but there are certainly circumstances in which its use is necessary, the dictionary be damned.