When to use under and over as prefixes rather than adverbs with past participles

Question

Is there a rule on when under and over are used as prefixes rather than adverbs when attached to past participles (and whether or not they are hyphenated)?

In general, it seems that both words are sufficient as adverbs, e.g., "this paper is under cited." However, we often see under and over attached as a prefix, e.g., "this paper is under-cited." In addition there are certain words where under/over are "built-in", e.g., "this company is understaffed." Is this simply a matter of convention or are there clearer rules on how the words should be paired? Are there differences in meaning when under is used as an adverb rather than a prefix (e.g., does "under cited" mean something different than "under-cited")?

Answer 1

I don't think there's a set answer to this question, partly because the usages tend to evolve over time.

For example, you can look up "he was over-dressed" on Google books. You'll find several hits, although many (yet not all) of them are from works written in the 19th century. Perhaps unsurprisingly, changing the search to "he was overdressed" returns more results, and most of those from more modern works, though exceptions can be found in either direction:

His dress was foppish; in fact he was overdressed, yet his garments were worn so easily they appeared to be a necessary part of him. He had a dark coat with lighter pantaloons... (E.T. Mason, 1891)

He was over-dressed in his suit and soon had the jacket slung over one shoulder. (P. Lovesey, 2003)

It seems that early on, timid writers are perhaps cautious about coining a new word, and may be inclined to use a hyphen. Later, as a phrase becomes more common and widely accepted, the hyphen gets dropped, the way hyphens tend to do over time.

Hyphens are sometimes like training wheels, it seems.