Russian Wikipedia has an article on:

осока

Wikipedia ^ru

Per Vasmer, possibly cognate with сечь (sečʹ, “to cut, to chop”) (1sg. секу́ (sekú)). Others propose a connection with Proto-Indo-European *h₂еḱ- (“sharp”) (whence Russian о́стрый (óstryj)), relating the term to Lithuanian ašakà (“fishbone”), also ãšaka.

• IPA^(key):

осо́ка • (osóka) f inan (genitive осо́ки, nominative plural осо́ки, genitive plural осо́к)

1. sedge

• осо́ковый (osókovyj)
• осо́чка (osóčka)

Ukrainian Wikipedia has an article on:

осока

Wikipedia ^uk

Per Vasmer, possibly cognate with сікти́ (siktý, “to cut, to chop”). Others propose a connection with Proto-Indo-European *h₂еḱ- (“sharp”) (whence Ukrainian го́стрий (hóstryj)), relating the term to Lithuanian ašakà (“fishbone”), also ãšaka.

• IPA^(key):

• Audio:

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осока́ • (osoká) f inan (genitive осоки́, nominative plural осоки́, genitive plural осо́к)

1. sedge

• осо́ковий (osókovyj)

• Bilodid, I. K., editor (1970–1980), “осока”, in Словник української мови: в 11 т. (in Ukrainian), Kyiv: Naukova Dumka
• Shyrokov, V. A., editor (2010–2025), “осока”, in Словник української мови: у 20 т. (in Ukrainian), volumes 1–15 (а – п'ять), Kyiv: Naukova Dumka; Ukrainian Lingua-Information Fund, →ISBN
• Ukrainian Lingua-Information Fund (2001–2025) “Словники України” online ‎ (in Ukrainian)