Yes, they are.
Something can be tame, or nonfrightening. The opposite of something scary would be something reassuring.
The sentence, Janet thought Sean's answer was very reassuring, is an example of how to use reassuring in a sentence.
reassuring sentence
A hand on someone's shoulder is reassuring.
reassuring advertising is aimed at existing customers.
Reassuring is the present participle of the verb reassure.
It can be (a reassuring reply, a reassuring hug). It is the present participle of the verb (to reassure) and may be a verb form, participial, noun, or adjective.
It is reassuring to know that I have a house to go home to at the end of the day.
Unsure
Closest in meaning to the word 'Reassuring' could be encourage, comfort, or cheer.
Closest in meaning to the word 'Reassuring' could be encourage, comfort, or cheer.
There are opposites of some adverbs and adjectives. The idea of "opposites" is conceptually weak and not all words have opposites.