Predicate adjective agreement

Unlike English, where adjectives never change, Czech adjectives typically reflect the noun they describe (with the exception of a few indeclinable borrowed words like fajn or super). When an adjective follows a linking verb (like být - to be, stát se - to become, zůstat - to remain, or zdát se - to seem), it is called a predicate adjective.

Key Rules:

• Nominative Case: Standalone predicate adjectives with conjugated forms of the verb být always remain in the nominative case. (Note: The instrumental case is sometimes used for temporary conditions with nouns, but this rule applies ONLY to nouns, never to standalone adjectives. The instrumental is typically used for adjectives following verbs expressing a change of state like stát se, or sometimes when být is in the infinitive, e.g., touha být prvním. Verbs like zůstat and zdát se can take either the nominative for everyday/neutral use or the instrumental for more formal/literary contexts).
• Gender and Number: The adjective must match the subject perfectly in gender and number (e.g., Ten dům je nový., Ta kniha je nová., and To auto je nové.).
• Unspecific Subject "To": When the subject is the unspecific demonstrative pronoun to (meaning "it" or "that" in a general sense), the predicate adjective must be in the neuter singular (e.g., To je dobré., Je to zajímavé.).
• Soft Adjectives: Soft adjectives (like inteligentní or moderní) do not change for gender in the nominative case. They always end in -í across all genders, both in the singular and plural.
• Plural Agreement: In the standard plural, endings depend on gender: masculine animate takes -í, masculine inanimate and feminine take -é, and neuter takes -á. If a mixed-gender group includes at least one masculine animate noun, the masculine animate ending takes priority. If a mixed-gender plural subject lacks a masculine animate noun (e.g., feminine and neuter), it defaults to the masculine inanimate/feminine ending -é. Note that in everyday spoken Czech (Common Czech), these plural endings often merge into -ý for all genders (e.g., Ty auta jsou nový.).
• Possessive Adjectives: Possessive adjectives (like otcův or matčin) can also act as predicate adjectives and must agree with the subject's gender and number (e.g., To auto je bratrovo., Ta kniha je matčina.).
• Short-form Adjectives: Some adjectives have short forms used primarily in the predicate. While rád (glad) exists exclusively in this short form, others like hotov (finished) or mrtev (dead) are highly formal or literary in modern Czech. They must agree with the subject (e.g., On je rád. vs. Ona je ráda.).
• Polite "Vy": When addressing one person formally using vy, the verb is plural (jste), but the adjective must be singular and match the person's natural gender (e.g., Vy jste velmi laskavá, paní Nováková.).