Chinese "empty word" 虚词

The term "empty word", or "虚词", in Chinese, refers to "a word or morpheme that has no lexical meaning and that functions as a grammatical link or marker, rather than as a contentive" according to Dictionary.com. Specifically, they include prepositions, conjunctions, auxiliary words or "Chinese particles", onomatopoeias, interjections, and adverbs[note1]. But in spite of its long history (back to 1890 to 1895, perhaps invented by a missionary or sinologist), the translation "empty word" has the connotation that the words, whoever utters, are not to be trusted, while "虚词" in Chinese is a purely technical, grammatical, term. This makes "empty word" a poor translation for "虚词", although no better one has been proposed. Incidentally, "hollow word", if it were used as a translation, may be closer literally ("hollow" for "虚"), but also has unwanted connotations.

Wikipedia considers the word "expletive" as the equivalent of "虚词". We need to think beyond the more common meaning of "expletive" here (words of profanity), and only consider syntactic expletive and expletive attributive. Because of its common usage of the word, neither is perfect in my opinion. In addition, be aware that an expletive in English is not quite equivalent to a "虚词" in Chinese. The latter is purely based on word class, while grammatical expletives in English are more context-sensitive. That is, all adverbs, prepositions, conjunctions, "Chinese particles", onomatopoeias, and interjections in Chinese are "虚词", with no exception, but there's no such simple rule in English.

Probably because of Wikipedia's English rendering of "虚词" as "expletive", pages of other languages use incorrect or not quite correct words, such as explétif in French, Kraftausdruck in German (words to express strong feelings, swears, expletives), where Formwörter^[note2] or mot-particule^[note3] may be a better term. But the Japanese page uses the Kanji 虚辞.

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[note1] This footnote is needed to avoid simplistic equivalence: English adverbs include almost all words of the construct adjective-ly, but Chinese adverbs are more or less limited to "very", "little", "all", "also", "probably", etc.
[note2] This word may have been coined by German sinologists about a century ago, as in Vergleich der wichtigsten formwörter der chinesischen umgangssprache und der schriftsprache
[note3]> as in Le mot-particule 之 tchē