🏷️ SCONJ: subordinating conjunction

Universal Dependencies · 7 key papers · all concepts

Part of: 🗨️ Natural language processing · 🌐 Universal Dependencies

A subordinating conjunction (SCONJ) is, in Universal Dependencies, the universal part-of-speech (UPOS) tag for function words that introduce a clause and mark it as dependent on another clause, as a complement or an adverbial modifier. Examples are English that, if and because.

Also: subordinating conjunction, subordinator, complementizer (for clause-complement markers), UPOS SCONJ

What it is

A subordinating conjunction is a small, closed-class word that turns a whole clause into a part of a larger sentence. In She left because it rained, the word because makes it rained an adverbial clause modifying left. In I know that he lied, the word that makes he lied the clausal complement (ccomp) of know. The coordinating conjunction does something different: it joins two units of equal rank (and, or). In Universal Dependencies it is tagged CCONJ (coordinating conjunction).

UD defines SCONJ as a conjunction that links constructions by making one of them a constituent of the other. Typically it marks the incorporated clause as an argument or an adverbial. Under UD's content-head design, a function word depends on the content word it serves rather than heading it (Marneffe et al. 2021). A SCONJ token therefore hangs from the predicate of the subordinate clause, usually through the relation mark (marker of a subordinate clause).

Examples

• English: I wonder whether/if she knows (complement clause). Although it was late, we stayed (concessive adverbial). He spoke as if he were ill.
• French: Je crois que tu as raison (complement). Il est parti parce qu'il pleuvait. Here the multiword parce que is linked internally by fixed (fixed multiword expression).
• German: Ich bleibe, weil es regnet. The clause it introduces is verb-final.
• Spanish: Dijo que vendría. Si llueve, no salgo.

Several neighbouring tags compete with SCONJ for the same words:

SCONJ words usually carry no features. The Czech treebanks follow a language-specific convention here, not a general UD rule. Forms such as aby and kdyby fuse a conjunction with a conditional auxiliary, so they bear Mood=Cnd plus Person and Number agreement.

Across languages

Subordination is coded very differently across languages, and the frequency of SCONJ tokens varies with it. Head-initial European languages use free subordinators regularly. Japanese, Korean and Turkish rely mostly on verbal suffixes, nominalizations and converbs (non-finite verb forms used for adverbial subordination). As a result, many of their clauses contain no SCONJ word at all. UD takes the word as its basic unit and splits clitics into separate words (Marneffe et al. 2021). Accordingly, Hebrew treebanks treat the prefixed subordinator še- "that" as its own SCONJ token.

In both English and French data, mark is the usual relation for SCONJ. fixed appears where a subordinator spans several words. That is common in French, with parce que, bien que and alors que.

In treebanks and research

The twelve-tag universal tagset of Petrov, Das and McDonald had no SCONJ category. Both kinds of conjunction fell under a single CONJ tag (Petrov et al. 2012). The UD v1 guidelines, published in October 2014, extended that set to 17 tags with SCONJ as a tag of its own. The v1 collection was described in a later overview (Nivre et al. 2016). The second version of the guidelines (UD v2) then renamed the remaining CONJ to CCONJ, which made the two-way distinction explicit (Nivre et al. 2020).

Mapping legacy tagsets onto this distinction can rely on feature-based conversion. Interset is one such intermediate representation: a shared inventory of morphosyntactic features and their values. UD's morphological features were based on it (Zeman 2008; Nivre et al. 2016).

Part-of-speech annotation is not always consistent across the UD corpora (Marneffe et al. 2017). Differences arise even between two treebanks of one language annotated under the same guidelines (Aggarwal & Zeman 2020). Words on the SCONJ/ADP/ADV boundary are one plausible place for such differences. One proposed check compares the UPOS trigram distributions of two treebanks (Aggarwal & Zeman 2020):

θpos(A,B) = KLcpos3(A,B) + KLcpos3(B,A)

Here A and B are two treebanks. KLcpos3, introduced by Rosa and Žabokrtský, is an asymmetric Kullback–Leibler divergence between their UPOS-trigram frequency distributions. Trigrams missing from one treebank are given a count of one. Summing both directions gives θpos, a symmetric measure proposed by Aggarwal and Zeman (Aggarwal & Zeman 2020).

Divergence also rises with smaller data and with differences in genre, so the authors derived genre-dependent thresholds. Whatever the genre mix, θpos at or below 0.5 counts as consistent annotation, and 4.0 or above as inconsistent (Aggarwal & Zeman 2020). Tagging before as SCONJ in one treebank and as ADP in another could contribute to such trigram differences.

For part-of-speech tagging and dependency parsing, a correctly tagged subordinator is useful evidence about where a clause begins and what kind of clause it may be. It can help a parser choose between relations such as ccomp and advcl (adverbial clause modifier). Still, words like that and if introduce both kinds of clause, and the choice also depends on the head predicate.

Key papers

The works this page cites, the most cited first; citations as counted by OpenAlex plus the papers of this library that cite the work, read 2026-10-24.

Related concepts

• Universal Dependencies — Universal Dependencies is a framework and an open collection of treebanks that annotates the grammar of many languages with one shared…
• Part-of-speech tagging — Part-of-speech tagging is the task of assigning each token in a text a grammatical category, such as noun, verb, adjective or determiner…
• Morphology — Morphology is the branch of linguistics that studies the internal structure of words. It covers how words are built from meaningful units…

More papers

Topics: 🔤 Part-of-speech tagging · 🌐 Universal Dependencies

Shelves: 🗣️ Language and Linguistics

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