Is there a different or better word for "underfill".

MS Word, Google, don't seem to recognize underfill as a word.

On Merriam Webster, they recognize it as a noun(paraphrased):

  1. a piece of steel manufactured with insufficient material

  2. an incompletely filled container

Underfill is also a material used in the PCB manufacturing process.

Why isn't it a verb similar to, but the antonym of, "overfill"?

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    Overfill is to overkill as underfill is to underkill, or as overstock is to understock. Not all prefixes are born equal. Except sometimes they are: overstate and understate. – Lambie Jan 31 at 16:16
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    One answer is that overfilling has far more dramatic and annoying consequences than underfilling would. I overfill the bath and it overflows, so that bathwater goes through the ceiling into downstairs apartment, fusing the lights, costing me who knows what for the damage. ‘Underfill’ the bath and it doesn’t even ‘underflow’: just leaves my tummy chilly. In short, there is insufficient demand for such a word. Speaking of ‘short’, there is a word for underfilling the container you are selling: ‘giving short measure’. – Tuffy Jan 31 at 17:02
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    jreese, ignore "red wiggly lines". – Michael Harvey Jan 31 at 17:41
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    I'm voting to close this question as off-topic because it looks like a peeve (or misplaced faith in the "authority" of software-based grammar checkers) – FumbleFingers Jan 31 at 18:05
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    I have to say that the question seems to me to be neither peevish nor naive. I think the poster just wants to know why a word as familiar to him or her as underfill doesn't show up in most dictionaries and doesn't enjoy the Microsoft Word seal of approval. – Sven Yargs Jan 31 at 23:33

The issue here is perhaps less black-and-white than the red squiggly lines under underfill in Microsoft Word (and other word processing programs) might lead one to believe.

Because under- is a prefix, it can legitimately attach to various root words to form meaningful words, even if those words aren't acknowledged by most dictionaries. Here is the entry for under- in The American Heritage Dictionary of the English Language, fifth edition (2010):

under- pref. 1. beneath or below in position: underground. 2. Inferior or subordinate in rank or importance: undersecretary. 3. Less in degree, rate, or quantity than normal or proper: undersized.

Definition 3 of under- is clearly applicable to underfill, just as it is to underachieve, underbid, underbuy, undercharge, undercount, underdo, underdress, underemphasize, underestimate, underexpose, underfeed, and underfund—to name just the under- verbs with root words starting with a, b, c, d, e, or f that AHDEL provides entries for. This dictionary doesn't include an entry for underfill—but that doesn't mean that it views underfill as illegitimate.

For many dictionaries, words built from an established root word and a particular prefix fall into a gray zone where the lexicographer must make an arbitrary decision about whether to include the term as a separate dictionary entry, a subentry, or not at all.

For example, Merriam-Webster's Eleventh Collegiate Dictionary (2003) deals with the twelve entries from AHDEL noted above as follows: underachieve (no separate entry, but listed under underachiever), underbid (separate entry), underbuy (no mention at all), undercharge (separate entry), undercount (separate entry), underdo (no mention at all), underdress (separate entry), underemphasize (separate entry), underestimate (separate entry), underexpose (separate entry), underfeed (separate entry), and underfund (separate entry).

Missing from both dictionaries are such words as underact, underbake, undercook, underemploy, and (of course) underfill. That all of these words are in use in published writing is evident from this Ngram: if you click the links beneath the graph you'll see links to instances of the word in Google Books (warning: some of the matches for underact are misreadings of "under act," and some of the other words' matches are to instances where the word in question is used as a noun rather than as a verb, as in the case of undercook). Note that the matches here generally exclude instances where the word is spelled with a hyphen between the prefix and the root word; and note, too, that Microsoft Word does not give the squiggly underline treatment to under-fill, even though most U.S. style guides (including the Chicago Manual of Style) advocate omitting the hyphen from under- words.

My main point is that even American dictionaries published within seven years of each other don't entirely agree with each about which under- words to give full entries to. To judge from the Ngram graph mentioned above, use of underfill has increased significantly in the past thirty years, so I would not be at all surprised to see it gain its own entry in the next edition of AHDEL. But with or without such recognition, it is clearly a word in common parlance that has a consistent, widely understood baseline meaning. And given that reality, dictionaries—and Microsoft Word—will eventually catch up with actual usage.

  • Odd how many 'under-' words have dictionary entries when I rarely use so many of them. This very text box wants to correct underfill to underflow with chrome, while IE wants to correct underfill to underhill! I can't think of the last time anyone has used the word underhill. Underflow maybe, but I would use other words to describe insufficient flow. Word suggests underfelt, which I've never even heard before. This question was brought forth because of the various spelling correction software suggesting it was misspelled, and then because of the missing entries in various dictionaries. Thanks! – jreese Jan 31 at 20:08
  • Interestingly enough, 'underfill' was more frequently used than 'overfill' from 1998 to 2004, but 'underfill' is on the decline now, according to the Ngram. – jreese Jan 31 at 20:20
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    That is indeed interesting, jreese, but I would hesitate to draw a firm conclusion about relative real-world use of overfill and underfill from Ngram results over a short period of time. Especially as we near the present, Ngram's results tend to get quite volatile, and I'm not at all sure that they are trustworthy. Still, there is no denying that underfill is in use and (at least in the United States) widely understood. – Sven Yargs Jan 31 at 20:27

In the UK, certainly, 'underfill' is a verb often used in relation to failure of equipment, processes, or humans to deliver expected quantities of material or product in a container, especially if there is a regulatory or contractual aspect to the shortfall.

"Pseudometabolic acidosis caused by underfill of Vacutainer® tubes." - medical journal; "According to the complaint, Starbucks underfilled its lattes" Daily Mail; "Laser Underfill and Overfill Check" industrial packaging equipment company; "Our customer is the bottler of a Cola drink, who was having issues with underfill and overfill of product in 500ml bottles on their Krones filling machine" bottling plant supplier (all UK)

  • I certainly agree that it is a word, and its meaning is quite readily understood in the verb form, it's just that the dictionary, google, MS Word don't think it is. I get suggestions to hyphenate it as "under-fill", or separate it into two words as "under fill", and neither of those seem right to me. – jreese Jan 31 at 18:21
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    It's in the Wordsense.eu dictionary - "transitive - To fill with an insufficient amount. antonym overfill". Google found me all of those examples above, and lots more about the specialised meaning in soldering electronic components; it should hardly need saying that the fact of something not being in your copy of MS Word's dictionary does not make it "not a word". – Michael Harvey Jan 31 at 18:46
  • Well Merriam Webster and Google and Microsoft Word all don't recognize it as a word or as a verb, while overfill is immediately recognized to be a verb. The Wordsense.eu dictionary is the only one that recognizes it as a verb so far, but I am using American English. – jreese Jan 31 at 18:56
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    I repeat, Microsoft Word is not a language authority. – Michael Harvey Jan 31 at 19:37
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    I remember Encarta from the 1990s when their dictionary and encyclopaedia were given away on CD-ROMs stuck on the fronts of computer magazines. – Michael Harvey Jan 31 at 20:13

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