About

Stop words are words that don't carry much meaning, and are typically removed as a preprocessing step before text analysis or natural language processing. This crate contains common stop words for a variety of languages. This crate uses stop word lists from Stopwords ISO and also from NLTK.

Usage

Use a language enum or its lookup code:

use stop_words::lookup;

if let Some(words) = lookup("en") {
    assert!(words.contains(&"the"));
}

// Unknown or disabled languages return None.
assert!(lookup("not-a-language").is_none());

lookup accepts a Language, a language code such as "en", or a borrowed String. It returns a static slice without allocating. Codes are matched exactly, without case or whitespace normalization.

With the iso or nltk feature enabled, lookup(stop_words::Language::English) returns the same list as lookup("en").

Language is the preferred language enum; the original LANGUAGE enum is deprecated since 0.10.1 and remains available for compatibility, including direct variant imports. Replace LANGUAGE with Language to migrate. They are distinct types accepted by both lookup functions. The existing get function is retained and panics for unknown or disabled languages. Call available_languages() to discover the codes enabled in a particular build.

For ISO languages, a lookup code is usually a two-letter ISO 639-1 code. Fictional constructed languages use three-letter codes (dot, dov, nav, qya, sjn, tlh, val), and NLTK-specific hinglish is supported when the nltk feature is enabled.

You can find a complete example of reading a text file and removing stop words here.

Features

Feature	Default	Contents
iso	yes	Stopwords ISO lists
nltk	no	NLTK lists, including NLTK-only languages
constructed	no	Experimental fictional-language lists
all	no	iso, nltk, and constructed together

Features are additive. Enabling constructed, for example, does not remove ISO or NLTK enum variants. When both iso and nltk provide a language, the NLTK list takes precedence, preserving the crate's existing behavior.

The crate continues to use the Rust 2021 edition.

Membership and customization

The crate returns static slices without allocating. For repeated membership checks or domain-specific changes, collect the slice into the set type your application needs:

use std::collections::HashSet;
use stop_words::lookup;

let Some(english) = lookup("en") else {
    return;
};
let mut words: HashSet<&str> = english.iter().copied().collect();
words.remove("computer"); // Preserve a meaningful domain term.
words.insert("project");  // Add an application-specific stop word.

assert!(!words.contains("computer"));
assert!(words.contains("project"));

Entries are returned as supplied by their source dataset. Normalize input and list entries consistently for case-insensitive matching; the crate does not impose language-dependent normalization.

Natural Language Availability

This crate supports all languages from Stopwords ISO and also from NLTK. Expand the table below to see a comprehensive description.

Language Coverage Table

ISO 639-1 Code	Language	Stopwords ISO	NLTK
aa	Afar
ab	Abkhazian
af	Afrikaans	✓
ak	Akan
sq	Albanian		✓
am	Amharic
ar	Arabic	✓	✓
an	Aragonese
hy	Armenian	✓
as	Assamese
av	Avaric
ae	Avestan
ay	Aymara
az	Azerbaijani		✓
ba	Bashkir
bm	Bambara
eu	Basque	✓	✓
be	Belarusian		✓
bn	Bengali	✓	✓
bh	Bihari languages
bi	Bislama
bo	Tibetan
bs	Bosnian
br	Breton	✓
bg	Bulgarian	✓
my	Burmese
ca	Catalan; Valencian	✓	✓
cs	Czech	✓
ch	Chamorro
ce	Chechen
zh	Chinese	✓	✓
cu	Church Slavic; Old Slavonic; Church Slavonic; Old Bulgarian; Old Church Slavonic
cv	Chuvash
kw	Cornish
co	Corsican
cr	Cree
cy	Welsh
da	Danish	✓	✓
de	German	✓	✓
dv	Divehi; Dhivehi; Maldivian
nl	Dutch; Flemish	✓	✓
dz	Dzongkha
el	Greek, Modern (1453-)	✓	✓
en	English	✓	✓
eo	Esperanto	✓
et	Estonian	✓
ee	Ewe
fo	Faroese
fa	Persian	✓
fj	Fijian
fi	Finnish	✓	✓
fr	French	✓	✓
fy	Western Frisian
ff	Fulah
ka	Georgian
gd	Gaelic; Scottish Gaelic
ga	Irish	✓
gl	Galician	✓
gv	Manx
gn	Guarani
gu	Gujarati	✓
ht	Haitian; Haitian Creole
ha	Hausa	✓
he	Hebrew	✓	✓
hz	Herero
hi	Hindi	✓
ho	Hiri Motu
hr	Croatian	✓
hu	Hungarian	✓	✓
ig	Igbo
is	Icelandic
io	Ido
ii	Sichuan Yi; Nuosu
iu	Inuktitut
ie	Interlingue; Occidental
ia	Interlingua (International Auxiliary Language Association)
id	Indonesian	✓	✓
ik	Inupiaq
it	Italian	✓	✓
jv	Javanese
ja	Japanese	✓
kl	Kalaallisut; Greenlandic
kn	Kannada
ks	Kashmiri
kr	Kanuri
kk	Kazakh		✓
km	Central Khmer
ki	Kikuyu; Gikuyu
rw	Kinyarwanda
ky	Kirghiz; Kyrgyz
kv	Komi
kg	Kongo
ko	Korean	✓
kj	Kuanyama; Kwanyama
ku	Kurdish	✓
lo	Lao
la	Latin	✓
lv	Latvian	✓
li	Limburgan; Limburger; Limburgish
ln	Lingala
lt	Lithuanian	✓
lb	Luxembourgish; Letzeburgesch
lu	Luba-Katanga
lg	Ganda
mk	Macedonian
mh	Marshallese
ml	Malayalam
mi	Maori
mr	Marathi	✓
ms	Malay	✓
mg	Malagasy
mt	Maltese
mn	Mongolian
na	Nauru
nv	Navajo; Navaho
nr	Ndebele, South; South Ndebele
nd	Ndebele, North; North Ndebele
ng	Ndonga
ne	Nepali		✓
nn	Norwegian Nynorsk; Nynorsk, Norwegian
nb	Bokmål, Norwegian; Norwegian Bokmål
no	Norwegian	✓	✓
ny	Chichewa; Chewa; Nyanja
oc	Occitan (post 1500)
oj	Ojibwa
or	Oriya
om	Oromo
os	Ossetian; Ossetic
pa	Panjabi; Punjabi
pi	Pali
pl	Polish	✓
pt	Portuguese	✓	✓
ps	Pushto; Pashto
qu	Quechua
rm	Romansh
ro	Romanian; Moldavian; Moldovan	✓	✓
rn	Rundi
ru	Russian	✓	✓
sg	Sango
sa	Sanskrit
si	Sinhala; Sinhalese
sk	Slovak	✓
sl	Slovenian	✓	✓
se	Northern Sami
sm	Samoan
sn	Shona
sd	Sindhi
so	Somali	✓
st	Sotho, Southern	✓
es	Spanish; Castilian	✓	✓
sc	Sardinian
sr	Serbian
ss	Swati
su	Sundanese
sw	Swahili	✓
sv	Swedish	✓	✓
ty	Tahitian
ta	Tamil		✓
tt	Tatar
te	Telugu
tg	Tajik		✓
tl	Tagalog	✓
th	Thai	✓
ti	Tigrinya
to	Tonga (Tonga Islands)
tn	Tswana
ts	Tsonga
tk	Turkmen
tr	Turkish	✓	✓
tw	Twi
ug	Uighur; Uyghur
uk	Ukrainian	✓
ur	Urdu	✓
uz	Uzbek		✓
ve	Venda
vi	Vietnamese	✓
vo	Volapük
wa	Walloon
wo	Wolof
xh	Xhosa
yi	Yiddish
yo	Yoruba	✓
za	Zhuang; Chuang
zu	Zulu	✓

NLTK also includes a non-ISO list for hinglish (lookup key: "hinglish") when the nltk feature is enabled.

Fictional Constructed Language Availability

The optional constructed feature provides small experimental lists for seven fictional languages. These lists were initially generated with ChatGPT in March 2023 rather than derived from authoritative corpora. Treat them as approximate starting points, not linguistically validated datasets. Source-backed corrections and corpus-derived replacements are welcome.

Language Coverage Table

ISO 639-3 Code	Language
qya	Quenya
sjn	Sindarin
tlh	Klingon
mis (dot is used here)	Dothraki
mis (dov is used here)	Dovahzul
mis (nav is used here)	Navi
mis (val is used here)	High Valyrian