From genericized trademark Sellotape, from cello(phane) + tape. The spelling with S- was to avoid an existing trademark on the word Cellophane itself.
sellotape (countable and uncountable, plural sellotapes)
- (Britain, Ireland, Australia, New Zealand) Adhesive tape.
sellotape (third-person singular simple present sellotapes, present participle sellotaping, simple past and past participle sellotaped)
- (transitive, Britain, Ireland, Australia, New Zealand) To seal with adhesive tape.