instantaneously

As an adverb instantaneously

is without any delay; in an instantaneous manner.

As an adjective undefined is

lacking a definition or value.

As an adverb instantaneously

is without any delay; in an instantaneous manner.

As an adjective simultaneous is

occurring]] or [[transpire|transpiring at the same time.

As adverbs the difference between spontaneously and instantaneously

is that spontaneously is in a spontaneous manner; naturally; voluntarily while instantaneously is without any delay; in an instantaneous manner.

As adverbs the difference between instantaneously and expressly

is that instantaneously is without any delay; in an instantaneous manner while expressly is in an expressive or explicit manner.

Instantaneously is a related term of promptly.

As adverbs the difference between instantaneously and promptly

is that instantaneously is without any delay; in an instantaneous manner while promptly is in prompt manner; both soon and quickly.

Directly is a synonym of instantaneously.

As adverbs the difference between directly and instantaneously

is that directly is in a direct manner; in a straight line or course while instantaneously is without any delay; in an instantaneous manner.

As a conjunction directly

is as soon as.

Straightway is a related term of instantaneously.

As adverbs the difference between straightway and instantaneously

is that straightway is directly while instantaneously is without any delay; in an instantaneous manner.

As a noun straightway

is a straight section of a racetrack.

As adverbs the difference between instantaneously and openly

is that instantaneously is without any delay; in an instantaneous manner while openly is in an open manner, visibly, not covertly.

Instantaneously is a related term of soon.

As adverbs the difference between instantaneously and soon

is that instantaneously is without any delay; in an instantaneous manner while soon is (label) immediately, instantly.

As an adjective soon is

occurring within a short time, or quickly.

Forthwith is a related term of instantaneously.

As adverbs the difference between forthwith and instantaneously

is that forthwith is immediately; without delay while instantaneously is without any delay; in an instantaneous manner.