v-

Understanding prothetic v- requires recognizing its phonological and sociolinguistic boundaries:

1. What it attaches to:
It applies to most native, everyday words starting with 'o-':

• Nouns: okno → vokno
• Pronouns: on/ona → von/vona, ono → vono, oni → voňi / voni
• Adjectives: ostrý → vostrý
• Adverbs: opravdu → vopravdu
• Numerals: osm → vosm
• Prepositions: o → vo, od → vod, ode → vode (e.g., vode mě). Note that when v- is added to prepositions like od (vod), it follows standard voicing assimilation rules based on the following word (e.g., vod stolu is pronounced [vot stolu]).
• Verbs and nouns starting with o-, ob-, od-, or ot-: obchod → vobchod, obejít → vobejít, odejít → vodejít, otevřít → votevřít

It can also appear word-internally when a prefix is attached to a stem or another prefix that starts with 'o-' (e.g., zaostřit → zavostřit, neomezený → nevomezený), or inside compound words where the second root starts with 'o' (e.g., modrooký → modrovoký, poloostrov → polovostrov). However, there are notable exceptions among native words that strongly resist it, such as otec, ovoce, and ovšem.

2. The Loanword Restriction:
Prothetic v- generally resists learned, technical, and foreign loanwords. Words like organizace or oceán usually do not take a v- in modern speech. However, older speakers of Common Czech (especially in traditional urban working-class environments) may use forms like vorganizace or volympiáda naturally and neutrally, whereas younger speakers might only use them in highly expressive or mocking contexts.

3. Geography, Register, and Age:
Historically widespread in Bohemia, it is absent in most of Moravia (except the western half) and Silesia. Linguistically, it evolved naturally from lip-rounding anticipation before the vowel /o/ (whereas formal Standard Czech uses a phonetic glottal stop or a smooth, continuous transition in connected speech instead). In regions where prothetic v- is absent, speakers pronounce the initial o- smoothly, with a glottal stop, or, in some specific dialects, with a prothetic h- (e.g., hoko, hokno). Sociolinguistically, its decline is a nationwide trend receding across all of Bohemia as well, driven by younger speakers and media standardization. Furthermore, it is almost exclusively a spoken phenomenon; it only appears in writing during informal texting, internet slang, or in literature/subtitles to deliberately depict colloquial speech.

4. Proper Nouns and Lexicalized Words:
Modern proper nouns (first names like Ondřej, Olga, and cities like Ostrava, Olomouc) generally resist prothetic v-. Adding it to these names sounds extremely archaic, rural, or heavily exaggerated. However, some words have historically fully standardized the prothetic v-, especially certain surnames and places (e.g., Vondra, Vorel, Votice). Do not confuse these or inherent v- words (voda, volat, voják) with the non-standard prothetic v-, which must be dropped in formal Standard Czech.

5. Vocalization of Prepositions:
A crucial mechanical consequence of adding prothetic v- is the vocalization of prepositions. When a word gains a prothetic v-, the non-syllabic prepositions v, k, s, and z must vocalize to ve, ke, se, and ze (e.g., v okně becomes ve vokně, k oknu becomes ke voknu, s oním becomes se voním, z okna becomes ze vokna).