All dictionaries I have looked at give the sole meaning of second to last as next to last (or penultimate and, in BrE, also second last). However, second to last is also used to mean what most folks call the third to last item in a series, especially in technical/scientific usage (see examples below). Can anyone provide documentation of this meaning in a reference work or do dictionaries omit this usage because they judge it to be incorrect (and if so, why not include it with a usage note)? I do not think previous related questions document this meaning adequately.
Related ELU/ELL questions:
"Usage of "second/third/fourth ... last"
Are there any differences between "penultimate", "the last but one" and "second to last"?
Dictionaries with second to/from last meaning only next to last or penultmate:
last
With the or possessive and an ordinal number. The one(s) the specified number of places from the end of a series. With of.
The year 1624, the second last of his life, was thus spent by Kin James, in [etc.]
She was the third-last of thirteen children. OED
Examples from Google Books where second to last and next to last are not the same i.e., second to last = third to last (in the usual meaning, or antepenultimate.
Modified Lag Task (Nback)
The task used in the present study was developed by Shelton et al. (2007). In this task, participants saw lists of 4 or 6 words and were asked to recall either the last, next to last (1-back), second to last (2-back), or third to last word (3-back) presented in the list J. T. Shelton, et al.; "A Comparison of Laboratory and Clinical Working Memory Tests and Their Prediction of Fluid Intelligence"; Intelligence, May 1, 2009
When the exact number of an instar is not known, it is often convenient to refer to these with terms such as middle, antepenultimate (second to last), penultimate (next to last), and/or ultimate instars. David L. Wagner; Catepillars of Eastern North America p.13 (2010)
Accent. For most scientific words, the accent is either on the next to last syllable or on the second to last syllable:
a. The accent is on the next to last syllable:
(1) When the word contains only two syllables; algae (AL·gae).
...
b. In all other cases, the accent is place on the "second" to last syllable (ar·TI·cul·lus)...Anthony M. Belmont; Acquiring a Scientific Vocabulary p.23 (2019)
S second to last hour
T S next to last hour
U T S last hourGregg DeYoung in Helaine Selin, ed.; Astronomy Across Cultures p. 484 (2021)
Rule C ('two bounce' rule). Have at least 3 searches; stop if both the last quote and the next to the last are larger than the second to the last. Peter E. Earl; Behavioural Economics, Vol. 1, p.168
... the local collections are formed using first, second, and third window, and second to last, next to last, and last window, respectively... Genome Research Vol. 14, p.706 (2004)
The cautionary instruction failed to cover the next to last and second to last prior questions to which responses indeed had been given and which contained the prosecutor's accusatory statements. Reports of Cases Decided in the Supreme Court of the State of Oregon, p.25 (1996)
Missing values are more common for the next-to-last births and especially the second-to-last births before... An Assessment of the Quality of Health Data in DHS-I Surveys, p.85 (1994)
The first digit gives the number of electrons in the last (outermost) shell..., the next two digits give the number of electrons in the next to last shell.., and the final two decimal digits give the number of electrons in the second to last shells... K. B. Lipkowitz et al. Reviews in Computational Chemistry, Vol. 20, p.293
(a) Last
(b) Next to last
(c) Second to last
Guide to Port Entry, Vol. 2, p.48 (2001)
As the last stage of this chain of full buffers completes its send command it waits a time BL before receiving its next token and unblocking the next to last stage of the chain. This stage then waits an additional time BL before the next token arrives, and the receipt of this token unblocks the second to last stage. This continues until the end of the chain... P. A. Beerel et al. A Designer's Guide to Asynchronous VLSI, p.71 (2010)
...the most weight was placed upon the last stage, followed by next to last, second to last, etc. The staging algorithm that we propose... The application of decomposition to transportation network (snippet)
"It doesn't matter anyway. You called second to last; I called next to last. That means I go after you."
"You're crazy! Next to last and second to last are the same thing," Ronny countered fervently.
You're the crazy one!" Billy shouted, his steel-blue eyes radiating fire. "It goes last, first to last—that's the same as next to last— and then comes second to last."
"You always have to have things your own way!" Ronny proclaimed without exaggeration. Bill Sullivan; Eleven Miles South of Half Moon Bay, p.33
These results are read from the frame F by starting with the last row of two boxes indicating a 2-cycle, the next to last row of two boxes indicating a second 2-cycle, the second from last row of three boxes indicating a 3-cycle, and finally the first row of four boxes indicating a 4-cycle. S. Keown; An Intoduction to Group Representation Theory (1975)
Photo 3 is the last mold; photo 2 next to last; and photo 1 second to last Transactions of the American Society for Steel Treating, p.390 (1924)
Rotation periods
Last ending in 1927 / Next to last / Second to last / Third to last / Fourth to last
B. Koehler et al.; Effect of Sec, Length of Feeding period..., p. 474 and repeated on p. 475 (1930)
Third from last row added ...
Second from last row added ...
Next to last row added ...
Last row added ...
Edward L. Thorndike, "The Curve of Work" in Psychological Review Vol. 19 (1912)
WORK EXPERIENCE [Form]
Job 1—Last or present position
Job 2—Next to last position
Job 3—Second to last position
N.Y. State Restaurant Association and E. Curtis; How to Cut Labor Costs, p.21 (1949)
(I've also found examples in U.S. and Canadian patents; however, the url links to the Google Book snippets aren't stable, so I've omitted them.)
A fair number of dictionaries don't have an entry for "second to last," which may foster to-each-their-own usage. The above examples essentially self-define how the authors are using the expression, even if incorrectly. My own hunch is that some may assume that because there are two well-known expressions, next to last and second to last, they must mean different things. The logic seems to be:
Next to last is considered to be the first from the last (although we don't usually say this) or penultimate
Second to/from last (Wikitionary has both) is therefore the next item, or the antepenultimate.
------------ EDIT 19/13/21 ---------------
This reasoning is explicitly stated in the first example's "NBack" Task" added today: next to last (1-back), second to last (2-back), or third to last word (3-back)
