Definify.com

Webster 1913 Edition

adv.

In an instinctive manner; by force of instinct; by natural impulse.

adv.

By force of instinct; without reasoning, instruction or experience; by natural impulse.

instinctively ‎(comparative more instinctively, superlative most instinctively)

Innately, by instinct, without being taught.
Fish instinctively know how to swim; most humans don't.

innately, by instinct, without being taught