IV

Short definition from Wiktionary

Adjective

1. 1
   Abbreviation of intravenous.

Noun

1. 1
   Initialism of intravenous injection.
2. 2
   Initialism of initialization vector.
3. 3
   Initialism of instrumental variable.
4. 4
   Initialism of immigrant visa.
5. 5
   Initialism of iodine value

Numeral

1. 1
   A Roman numeral representing four (4).

Symbol

1. 1
   Specifying an oxidation state of 4
2. 2
   Ⅳ, the Roman numeral four (4).