Solutions Sis's sib has 17 entries with similar clues

• 3-letter words
• sisBro's sibling
• 4-letter words
• hissSnake's sibilant sound
• lenaA river in Siberia
• 5-letter words
• sashamalia's sibling
• taigaSiberian forest
• 6-letter words
• oldestLike the firstborn sibling
• nephewA sibling's child
• sisterSibling
• 7-letter words
• brotherMale sibling
• sistersFemale siblings
• 8-letter words
• dialysisPhone sibling after years, clearing bad blood
• synopsisRecap after small glass of beer upended sibling
• 10-letter words
• bering-seaPart of Pacific between Siberia and Alaska
• 11-letter words
• vladivostokRussian city Trans-Siberian railway terminus
• 14-letter words
• fortune-tellerSibyl
• identical-twinLook-alike sibling
• 21-letter words
• first-degree-relativeA person's parent, sibling, or child