What is the definition of “soliloquy”?
a.
a speech given by a character in the presence of others, but unheard by them
b.
a monologue that reveals a character’s innermost thoughts
c.
conversation between characters
d.
a speech given by a character to other characters on stage

The answer is B: a monologue that reveals a character’s innermost thoughts.

A soliloquy is a dramatic device in which a character talks to himself revealing his or her feelings or thoughts as if it was an inner reflection of the most intimate or personal nature. If while the soliloquy is being delivered there are other characters present on the scene, they are disregarded by the speaker and one is to understand that they can´t hear the speaker.  

The definition of "soliloquy" is a monologue that reveals a character’s innermost thoughts.

Explanation: A soliloquy is a monologue, also known as a long one-sided conversation, given by a particular character in a play. By means of a soliloquy, a character is able to transmit the way he/she feels and to express what is going on in his/her mind, that is to say to reveal his/her most inner thoughts. Soliloquys are frequent in Shakespeare's plays, especially in Hamlet, where the main character talks to himself and shows his concerns about whether killing Claudius is the right thing to do.