Agreement with coordinated subjects

This agreement applies primarily to the past tense l-participle (e.g., dělali), passive participles (e.g., byli vybráni), and predicate adjectives.

The 'One Dog' Rule:
The masculine animate noun doesn't have to be human, nor does it need to be the logical focus of the sentence. A hundred women and one dog (pes) will trigger the -i ending: Ženy a pes šli. (The women and the dog walked.)

Grammatical vs. Natural Gender:
Agreement is generally based on grammatical gender, not biology. For example, děvčata (girls) refers to female humans but is grammatically neuter plural, so it takes the -a ending: Děvčata a štěňata šla. (The girls and the puppies walked.) Conversely, words like rodiče (parents), koně (horses), or lidičky (little people) might look like feminine or inanimate nouns, but they are grammatically masculine animate and trigger the -i ending: Rodiče a děti šli. (The parents and children walked.) Note a special exception for koně: if it refers to inanimate objects (like wooden horses or gymnastic horses), it takes the inanimate -y ending: Dřevěné koně a vozy stály. (The wooden horses and carts stood.) However, Czech sometimes allows for semantic agreement with collective nouns representing people (e.g., dav, rodina). Standard codified Czech grammar requires grammatical agreement within the same coordinated clause (Sestra a její rodina nás přivítaly.). Applying semantic agreement in a single clause with a 3rd-person verb is grammatically incorrect. Semantic agreement is universally accepted and preferred in subsequent clauses or sentences where the collective noun is the subject: Rodina přijela včas. Byli ale velmi unavení. (The family arrived on time. But they were very tired.)

Word Order Exception (Closest-Conjunct Agreement):
In standard S-V order, masculine animate nouns take highest priority. However, if the verb comes before the subject (V-S order), Czech allows the verb to agree with the noun immediately following it. This closest noun can even be singular, resulting in a singular verb: Do třídy vešla studentka a učitelé. (The female student and the male teachers entered the classroom. - The verb vešla agrees with the singular feminine studentka, even though učitelé is masculine animate plural).

General Fallback Rule (The Hierarchy):
To determine the correct ending, follow this strict hierarchy:
1. If there is at least one masculine animate noun, the ending is -i.
2. If ALL subjects are neuter plural, the ending is -a.
3. For everything else (feminine, masculine inanimate, neuter singular, or any mix like feminine + neuter plural), the ending defaults to -y: Ženy a stroje pracovaly. (The women and the machines worked.) Ženy a koťata spaly. (The women and the kittens slept.)

The Neuter Singular Trap:
If a coordinated subject consists entirely of neuter nouns, but at least one of them is singular, the verb ending defaults to the feminine/inanimate -y instead of the neuter plural -a: Kotě a štěňata spaly. (The kitten and the puppies slept.)

The Děti, oči, uši Exception:
The nouns děti (children), oči (eyes), and uši (ears) are grammatically feminine in the plural. When they are coordinated with any non-masculine-animate noun, the resulting agreement is feminine -y: Děti a koťata si hrály. (The children and the kittens played.)

Person Hierarchy:
When subjects involve different grammatical persons, the 1st person takes priority over the 2nd and 3rd person, and the 2nd person takes priority over the 3rd. The verb will be in the plural form of the highest-priority person: Já a pes jsme šli. (The dog and I walked.)

The s (with) Construction:
When a subject is formed using a noun followed by s + instrumental (e.g., otec se synem - a father with his son), Czech allows two options. You can use plural agreement to emphasize the pair acting together (Otec se synem šli.) or singular agreement matching the first noun (Otec se synem šel.).

Spoken vs. Written Czech:
Because -i and -y are pronounced exactly the same [ɪ] in modern Czech, this specific distinction is purely orthographic. However, the neuter plural ending -a is pronounced [a] and remains distinct in speech. In casual spoken Czech, speakers often default to the [ɪ] sound for all plural past-tense verbs, but you need to be careful with the exact endings when writing formal texts!