When constructing a puzzle, I sometimes see a word that will fit beautifully with most of the letters of the crossing words in that section of the grid, except for one problem. It has fewer letters than the number of squares in that position. There are some options that can help me resolve the issue, i.e., increase the letter count of the base word* (usually the word in its first alphabetical appearance in the dictionary) to match the number of squares I'm trying to fill.
I call these devices Letter Count Manipulation, partly because that's what's going on---the number of letters in a word is being tinkered with---and partly because it makes for a spiffy initialism, LCM. In the vast majority of cases the LCM is for expediency or convenience. It's gratuitous. It's there only because it boosts the letter count and makes it easier to fill the grid, not because it adds value or interest to the puzzle.
One of the most frequently encountered methods to manipulate letter count is to take a base word, typically a noun or verb, and add an S, an ES, or drop a Y and add IES. The resulting longer word is what I call a Plural Of Convenience, or POC, and I have posted about POCs elsewhere on this blog.
Another LCM option is to take a base word that is a verb and change it into a noun. Consider the verb ASPIRE. By adding an R, I can take that six-letter word and make it fit a seven-letter slot. An additional letter-count boost to eight can be had by adding on a POC. We would go from ASPIRE to ASPIRER to ASPIRERS. A clue starting out along the lines of "One who...", or "Those who..." is often a tell-tale sign that a noun-to-verb LCM has gone down.
There are two more ways verbs can be used for LCMs. The first is shifting the tense, usually from the present to the past, and the second is shifting from the base form of the verb to a gerund/present participle. The typical tense shift will amp up the letter-count by two, e.g., CAMP to CAMPED (a 50% letter-count increase), while going to the gerund can net a three-letter boost, e.g., CAMP to CAMPING (a 75% letter-count increase).
Adjectives can provide a rich lode for mining LCMs, as when one takes on an adverb's clothing and gets a two-letter uptick, for example, from APT to APTLY. For some advanced LCM, you can combine the verb-to-gerund and the adjective-to-adverb ploys to give some amazing letter-count boosting. Consider the base word FIT. An LCM to FITTING gives a 133% letter-count increase, while doubling up on LCMs to FITTINGLY gives a whopping 200% letter-count and subsequent grid fill increase. Is there an equivalent 200% increase in value/meaning/interest? Not for me, not even close.
Another LCM that I see regularly is shifting to the comparative or superlative form of an adjective. This can net a two-, three-, or even four- or more letter bump. A good example would be FAR, FARTHER/FURTHER, FARTHEST/FURTHEST , with the superlative giving a 166% grid-space-filling increase. The champion in this department, methinks, would be FITTINGEST, coming in with a 233% increase in grid-filling power.
The common thread for all LCM's is increasing the amount of grid space that gets filled without adding a commensurate amount of value or interest to the puzzle. LCM's just make it easier to fill the grid. They make the "artful arrangement of words crossing one another" less artful.
I think LCM's are like abbreviations, partial phrases, foreign words, random Roman numerals, crosswordese, and the like. Any of these used judiciously to facilitate filling the grid of an otherwise excellent puzzle would be unremarkable and above reproach. It's when they are used excessively that, for me, they become intrusive and degrade the overall quality and integrity of the puzzle, and diminish my enjoyment of the solving experience.
Be on the lookout for LCMs in a puzzle near you.
*By base or core word I mean the form of the word that cannot be reduced further without losing the meaning of the word. Remove any of its letters and it becomes meaningless or its meaning is completely changed, or it loses its standing as a word and becomes, for example, an abbreviation.