from The American Heritage® Dictionary of the English Language, 5th Edition.
- noun A clitic that is attached to the beginning of another word.
- adjective Of or relating to a proclitic or proclisis; forming an accentual unit with the following word.
from The Century Dictionary.
- 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.
- noun In Greek grammar, a monosyllabic word which leans upon or is so closely attached to a following word as to have no independent accent.
from the GNU version of the Collaborative International Dictionary of English.
- adjective (Gr. Gram.) Leaning forward; -- said of certain monosyllabic words which are so closely attached to the following word as not to have a separate accent.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun linguistics A
cliticwhich 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 American Heritage® Dictionary of the English Language, 4th 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.