What is an antonym for the word motive?

There isn't a single perfect antonym for "motive," as its meaning depends on context. Here are some options depending on the specific meaning:

If "motive" means "reason":

* Lack of reason

* Unintentional

* Accidental

* Spontaneous

If "motive" means "goal" or "purpose":

* Aimless

* Pointless

* Random

* Meaningless

If "motive" means "driving force":

* Inertia

* Passivity

* Indifference

* Apathy

If "motive" refers to a hidden intention:

* Honest

* Open

* Transparent

* Genuine

Choosing the best antonym depends on the specific context and nuance you want to convey.