from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A clitic that is attached to the beginning of another word.
- adj. Of or relating to a proclitic or proclisis; forming an accentual unit with the following word.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A clitic which phonetically joins with the following word. In English, the dialectal form t' is an example. In Arabic, conjunctions and prepositions that have only one letter, such as و (wa-), always attach as a prefix to the following word.
from the GNU version of the Collaborative International Dictionary of English
- adj. Leaning forward; -- said of certain monosyllabic words which are so closely attached to the following word as not to have a separate accent.
from The Century Dictionary and Cyclopedia
- In Greek grammar, dependent in accent upon the following word: noting certain monosyllabic words so closely attached to the word following as to have no accent.
- n. In Greek grammar, a monosyllabic word which leans upon or is so closely attached to a following word as to have no independent accent.
New Latin procliticus : pro-2 + Late Latin (en)cliticus, enclitic; see enclitic.(American Heritage® Dictionary of the English Language, Fourth Edition)
Maybe all it indicates is that un– was really a proclitic instead of a prefix all along, but we never knew it until someone came up with this usage that revealed it.
Not what you would expect from a proclitic … Also, “I’m” would be a bit funny then.