Grammatik7-Buchstaben-Regel

Russian spelling has a small rule that clears up a lot of “irregular-looking” endings. After seven particular letters you are simply not allowed to write certain vowels: you swap ы → и, я → а and ю → у. It’s often called the 7-letter rule (or the spelling rule). Once you know it, endings like кни́ги and хоро́ший stop looking like exceptions.

The seven trigger letters

The rule applies right after any of these seven consonants:

• Velars: г, к, х
• Hushers (sibilants): ж, ч, ш, щ

Whenever an ending would put ы, я or ю directly after one of these, you replace it:

и, not ы

This is by far the most common case. It shows up in noun plurals and other endings that would “expect” ы:

• кни́ги (books) — not книгы
• ру́ки, но́ги (hands, legs)
• кни́жки, ло́жки (little books, spoons)

It also governs many adjective endings after a velar or husher stem:

• больши́е (big, pl.), ти́хие (quiet, pl.)
• ру́сский (Russian), хоро́ший (good)

Compare a normal stem, where ы is allowed: студе́нт → студе́нты (students), but кни́га → кни́ги — because г forces и.

а, not я · у, not ю

These two turn up mostly in verb endings and a handful of noun forms. Second-conjugation verbs whose stem ends in a husher take -ат / -у instead of the “expected” -ят / -ю:

Even though these are second-conjugation verbs (you’d expect -ят and -ю), the husher forces -ат and -у: они́ де́ржат, я держу́.

The same а-not-я spelling appears in nouns after a husher: ча́ша (cup), кры́ша (roof) — written ша, never шя.

Why it matters

The rule overrides the ending you’d otherwise predict from the hard/soft pattern. That’s why some endings look irregular even though they are perfectly regular — they’re just obeying spelling, not grammar:

• студе́нты keeps ы (normal stem), but кни́ги must use и because of г.
• A husher-stem 2nd-conjugation verb looks like it took a 1st-conjugation ending — but слы́шат is just -ят written legally.

So when an ending surprises you, check the last stem consonant first: if it’s one of the seven, the spelling rule is probably doing the work.

Don’t confuse it with the 5-letter rule

There is a separate spelling rule about о vs е after ж, ч, ш, щ, ц (unstressed → е). That one is often called the 5-letter rule and involves a different set of letters (it adds ц) and different vowels (о / е).

Common mistakes

• Writing ы after a velar.
  книгы (wrong) → кни́ги (correct)
• Writing ы in a husher adjective.
  хорошый (wrong) → хоро́ший (correct)
• Using -ят / -ю after a husher.
  слышят, слышю (wrong) → слы́шат, слы́шу (correct)
• Writing я in a husher noun.
  чашя (wrong) → ча́ша (correct)

Summary

• After г, к, х, ж, ч, ш, щ: write и (not ы), а (not я), у (not ю).
• и-not-ы is everywhere: plurals кни́ги, ру́ки, ло́жки and adjectives больши́е, ру́сский, хоро́ший.
• а-not-я and у-not-ю mainly in verbs: они́ слы́шат, де́ржат; я слы́шу, держу́.
• The rule overrides the “expected” ending, so кни́ги vs студе́нты is spelling, not grammar.
• Keep it separate from the 5-letter rule (о / е after ж ч ш щ ц).