| impetuous(noun, adjective, thoughtless, impulsive, thinking) |
| inborn(adjective, natural, instinctive, automatic, involuntary) |
| ingrained(adjective, natural, instinctive, automatic, involuntary) |
| inherent(adjective, natural, ignorant, instinctive, automatic) |
| innate(adjective, natural, ignorant, instinctive, automatic) |
| instinctual(adjective, natural, instinctive, unwilling, automatic) |
| intrinsic(adjective, natural, instinctive, automatic, involuntary) |
| intuitional(adjective, natural, instinctive, automatic, involuntary) |
| intuitive(adjective, passionate, violent, abrupt, instinctive) |
| knee-jerk(adjective, natural, instinctive, unwilling, automatic) |
| native(adjective, natural, instinctive, automatic, involuntary) |
| normal(adjective, natural, instinctive, automatic, involuntary) |
| rash(noun, adjective, passionate, violent, careless) |
| regular(adjective, natural, instinctive, automatic, involuntary) |
| rooted(adjective, natural, instinctive, automatic, involuntary) |
| second-nature(adjective, instinctive, automatic, involuntary, reflex) |
| snap(noun, adjective, free, informal, casual) |
| typical(adjective, natural, instinctive, automatic, involuntary) |
| unlearned(adjective, natural, instinctive, automatic, involuntary) |
| abrupt(adjective, passionate, violent, thoughtless, impulsive) |