What is English word IS?

Definitions of IS

1. Abbreviation of Islands. (also Is.)
2. inflection of be
3. (now, colloquial) Used in phrases with existential there when the semantic subject is a third-person plural.
4. (rare) Alternative form of i's..
5. (Geordie) Alternative spelling of us ("me")..
6. Initialism of Islamic State.
7. Initialism of Interior Salish.
8. Initialism of International Sign.
9. (computing) Initialism of information system(s).
10. (politics) Initialism of international studies.
11. (finance) Initialism of implementation shortfall.
12. plural of I.