по-ру́сски vs по-ру́сскому

po-russki vs po-russkomu — in Russian vs in the Russian manner/style

What it really means

По-ру́сски is the standard adverb meaning “in Russian,” especially for speaking, writing, reading, or behaving in a Russian way: Он говорит по-ру́сски. It is a fixed adverb formed with по- and is written with a hyphen. This is the normal answer to “How do you say it in Russian?”

По-ру́сскому is not the standard replacement for that adverb. It is normally the dative singular masculine or neuter form of the adjective ру́сский after по, as in по ру́сскому языку (“in/for Russian language [class]”) or по ру́сскому обычаю (“according to Russian custom”). In colloquial speech, people may occasionally use по-русскому to mean “in a Russian manner,” but careful learners should choose the construction that fits the noun or use по-ру́сски for language manner.

Examples in natural speech

Как это будет по-ру́сски?
How will this be in Russian?
Он читает по-ру́сски без словаря.
He reads in Russian without a dictionary.
У нас экзамен по ру́сскому языку.
We have an exam in Russian language.
По ру́сскому обычаю гости сначала снимают обувь.
According to Russian custom, guests first take off their shoes.
Она объяснила правило по-ру́сски, а не по-англи́йски.
She explained the rule in Russian, not in English.

Common mistakes

Do not use по-ру́сскому for the ordinary language adverb: say говорить по-ру́сски. In phrases with a noun, write по ру́сскому языку or по ру́сскому обычаю as a preposition plus adjective, not an adverbial hyphenated form. Distinguish the spelling and meaning even though casual speech may blur them.

Memory tip

Language manner is по-ру́сски; по ру́сскому normally modifies an understood or expressed masculine/neuter noun.

Frequently asked questions

Is по-русскому ever acceptable?

It is acceptable when по introduces the adjective form, especially with an expressed or understood noun: урок по русскому (языку). As a pure language adverb, use по-ру́сски.

Why is по ру́сскому обычаю written without a hyphen?

Here по is a preposition governing the dative adjective phrase “according to Russian custom,” not the prefix of the adverb по-ру́сски.

What is the feminine counterpart after по?

The adjective agrees with its noun: по ру́сской традиции, while the fixed manner adverb remains по-ру́сски.

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