1 instantaneous, instant, abrupt, sudden, swift; spontaneous, instinctive, triggered, unhesitating, unthinking, automatic, reflex, knee-jerk:
Why is your immediate reaction always to say 'It cannot be done'?
2 direct, nearest, next, closest, adjacent, proximate; nearby:
Although he had cancer, the immediate cause of death was pneumonia. Is there a phone box in the immediate vicinity?
3 existing, present, current, actual, pressing, urgent:
The immediate problem is to find a way of getting out of here.