Select the most appropriate one-word substitution for the given group of words.  A speech to oneself, alone

Colloquial Melancholy  Dialogue Soliloquy

Soliloquy

The most appropriate one-word substitution for the given group of words is soliloquy. Colloquial means informal or relaxed in style. Melancholy means sad or pensive. Dialogue means a conversation between two or more people. Soliloquy means a speech to oneself, alone.