tõu

Tíu is the Icelandic word for the number ten and functions as a cardinal numeral in counting, ages, dates, and other quantitative expressions. It is written with an acute accent on the í and is pronounced with a lengthened vowel.

In the Icelandic numeral system, tíu serves as the base for ten. Numbers from eleven to nineteen have irregular forms (for example ellefu, tólf, and others), while tens are expressed with separate words such as tuttugu (20) and þrjátíu (30). Numbers from 21 to 99 are typically formed with a tens word followed by the conjunction og and the unit, for example tuttugu og einn for 21 or þrjátíu og sex for 36. This pattern of tens-plus-units is common in Icelandic, while the teens retain unique forms.

Etymology and related forms: tíu is cognate with the Danish ti and the Norwegian ti, reflecting a shared North Germanic origin. The Icelandic form is descended from Old Norse tíu, and the word is part of a broader Germanic numeral tradition in which ten appears with similar phonetic patterns across the region.

Usage and context: beyond simple counting, tíu appears in arithmetic, timekeeping, and commonly in historical or literary texts that use traditional number forms. It also appears in the formation of larger numerals and in compound expressions that reference quantities in everyday language.