2714: Comparing Asleep and On Fleek May 26

There is a prefix a-, found in many verbs, that carries meanings related to away, up, on, or out, as in ‘arise’, ‘awake’ or not as a verb in ‘afoot’ or ‘aside’, but is probably more typically used for conditions of something ongoing, like ‘aglow’, ‘asleep’, and ‘asunder’. This originates from the word ‘on’ and functions similarly as verbs with the on-prefix. It can be used in some other ways too, but the prefix is generally considered non-productive, which is to say that it is not applied onto words aside from a set list now. 

On still does carry the meaning of condition as seen in phrases like ‘on fire’ (compare ablaze) but while it is rare, the prefix a- might still be understood as generative if usually humorous and informal, like “I’m busy a-working”. In the perhaps now outdated slang term of the last decade “on fleek”, or more common “on point” or to have something “on lock”, on has taken on some renewed vigor again in the sense of condition (of). This is not enough to make it productive, it does show that there is some mileage in a conditional-on.

2535: Why 'Un-' Doesn't Assimilate Like 'In-' (Ir- Il- Im-) Nov 21, 2021

The prefix 'in-' assimilates to different sounds depending upon the context, becoming 'im-', 'il-', and 'ir-', but this is not true of 'un-', which is similar both semantically but more importantly, phonetically. For instance, 'in-' + 'responsible' is 'irresponsible', but 'un-' + 'responsive' is 'unresponsive'. This was true of the negating prefix 'in-' in Latin whence this use was borrowed, and while 'un-' is distantly related to this, it is really considered to be of a Germanic root where this does not happen.

2294: Disfix Mar 28, 2021

There are many types of affixes, including ones which are not only additive, whether in the middle or on the ends [1]. One more for instance is the so-called 'disfix' which is a type of affix (such as in French a suffix) which is subtractive, meaning is causes a loss to the stem. Usually, this happens to the final segment of the stem, just before the disfix. For instance, with this pluralization from French:

bœuf (cow) as [bœf] --> bœufs (cows/cattle) as [bø]

such that the [f] is deleted in the plural. This also happens with adjectives such as

fausse (wrong (fem.)) as [fos] --> faux (wrong (masc.)) as [fo].

This process is common in certain North American native languages like Alabama, Choctaw, or other Muskogee languages.

1228: English Right-Hand Rule Apr 20, 2018

There is a reason why negative affixes are going to be prefixes in English is the same reason why derivational affixes such as '-al', '-ness' and '-ate' will be suffixes. English has what is called the "English right-hand rule" which states that usually, the right-most element is the head of the word, and will determine the syntax and or meaning. This is true of most adjectives, compounds where the first element acts almost like an adjective, and affixes. With the latter, negating prefixes such as 'in-', 'un-' and 'non-' all can be attached to adjectives (among other things) and the word will still remain an adjective (or whatever else) whereas the aforementioned suffixes will all make a word of one part of speech become a word of another lexical class. This is the case with most affixes in other Germanic languages as well, though there are a few notable exceptions within each, and is one of many significant reasons why English will not be considered a Romance language despite strong influences from vocabulary.
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