After completely failing my Czech assignment on building the plural form of nouns, I decided to take a data-driven approach: parse the entire [MorfFlex CZ 2.1](https://ufal.mff.cuni.cz/morfflex) linguistic dataset using [Morph](https://morph.to/) and create a queryable database (126 million rows!), select all nouns in the nominative case, categorise every one of them by gender, and extract the actual plurality patterns used in the language.

Here's what I found.

# The Data

|Gender|Nouns Analyzed|Unique Patterns|
|:-|:-|:-|
|Feminine|196,334|174|
|Neuter|65,211|106|
|Masculine Animate|15,834|306|
|Masculine Inanimate|26,723|222|

**Total: 808 distinct plural transformation patterns.**

A note on the data: MorfFlex is comprehensive and includes many systematically derived forms. For example, almost any verb can become a neuter verbal noun ending in *-í* (*psát -> psaní*), and adjectives regularly form abstract feminine nouns in *-ost* (*krásný -> krásnost*). So the raw counts are inflated for these patterns - but the rules themselves are still productive and useful to know!

# The actual rules

# Neuter

Neuter is probably the easiest to learn.

**Words ending in -í stay the same.** This covers verbal nouns (*přání*, *stavení*) and place names (*náměstí*, *nádraží*). Singular and plural are identical.

**Words ending in -o change to -a.** Standard hard neuters: *okno* becomes *okna*, *město* becomes *města*, *jablko* becomes *jablka*.

**Words ending in -e or -ě stay the same.** Soft neuters like *moře*, *pole*, and place words like *hřiště* don't change.

**Latin -um becomes -a.** Borrowed words like *muzeum* become *muzea*, *centrum* becomes *centra*, *stipendium* becomes *stipendia*.

**Baby animals are special: -e/-ě becomes -ata.** This is definitely the cutest pattern. *Kuře* (chick) becomes *kuřata*, *kotě* (kitten) becomes *koťata*, *štěně* (puppy) becomes *štěňata*. Even *kníže* (prince) follows this pattern and becomes *knížata*.

**Greek words ending in -ma add -ta.** Words like *téma* become *témata*, *drama* becomes *dramata*.

# Feminine

**The -ost rule: just add -i.** Abstract nouns like *možnost* become *možnosti*, *radost* becomes *radosti*. Very predictable once you recognize the ending.

**Hard feminines: -a becomes -y.** Pretty simple pattern. *Žena* becomes *ženy*, *kniha* becomes *knihy*, *škola* becomes *školy*.

**Soft feminines stay the same.** Words ending in -e or -ě don't change: *ulice* stays *ulice*, *restaurace* stays *restaurace*, *přítelkyně* stays *přítelkyně*.

# Masculine inanimate

**Hard consonants take -y.** *Hrad* becomes *hrady*, *strom* becomes *stromy*, *most* becomes *mosty*. In my data, endings like -n, -t, -k, -r, -l, -s, -d each covered thousands of nouns.

**Soft consonants take -e.** *Stroj* becomes *stroje*, *pokoj* becomes *pokoje*, *koš* becomes *koše*.

**Latin -ismus drops the -us.** *Turismus* becomes *turismy*, *organismus* becomes *organismy*.

**Diminutives with -ek lose the e.** This can catch you off guard. *Háček* becomes *háčky* (not *háčeky*), *stolek* becomes *stolky*, *dárek* becomes *dárky*.

**Same with -ec: the e disappears.** *Tanec* becomes *tance*, *konec* becomes *konce*.

# Masculine animate

This is where it gets a bit complicated. Despite having the fewest nouns (15,834), this gender has the most patterns (306). But there's logic to it.

**Hard consonants + i, but with softening.** When you add *-i*, hard consonants change and become soft:

* k becomes c: *člověk* becomes *lidé* (ok that one's irregular), but *žák* becomes *žáci*
* h becomes z: *vrah* becomes *vrazi*, *soudruh* becomes *soudruzi*
* ch becomes š: *Čech* becomes *Češi*
* r becomes ř: *doktor* becomes *doktoři*

**Soft consonants just add -i, no changes.** *Milionář* becomes *milionáři*, *muž* becomes *muži*, *hledač* becomes *hledači*. The consonant is already soft, so nothing extra happens.

**Words ending in -l take -é.** *Učitel* becomes *učitelé*, *přítel* becomes *přátelé*, *ředitel* becomes *ředitelé*.

**The -ista crowd takes -isté.** Professions and ideologies: *specialista* becomes *specialisté*, *fotbalista* becomes *fotbalisté*, *turista* becomes *turisté*. (Colloquially, recognise you'll also hear *-isti*.)

**The formal -ové ending.** Used for professions and titles when you want to sound respectful: *geolog* becomes *geologové*, *kolega* becomes *kolegové*.

**Words ending in -ec/-ce become -ci.** *Sportovec* becomes *sportovci*, *zástupce* becomes *zástupci*.

# The interactive guide

I turned all of this into a detailed educational article with interactive examples where you can type any noun and see its plural form explained:

[**How to Build Plural Form of Czech Nouns**](https://morph.to/learn/nouns/plurals)

# If you're hungry for technical details

I queried nominative case nouns grouped by lemma and gender, extracted the singular/plural transformation by finding the common prefix and comparing endings, and then counted pattern frequencies. Used reservoir sampling to get representative examples across the alphabet instead of just words starting with A. Happy to share CSV files with a detailed breakdown if someone is interested or even query some data for you :D

Hope this helps someone!!

Instead of touching grass, I analyzed 304,102 Czech nouns