* Verb: This is the most common use, describing the action of something flashing intermittently. Example: "The candle flame flickered in the wind."
* Adjective: It can describe something that is flashing intermittently. Example: "The flickering lights gave me a headache."
* Noun: This is less common, but "flickering" can also be used as a noun to refer to the act of flashing intermittently. Example: "The flickering of the candlelight cast dancing shadows on the wall."
To determine the correct part of speech, you need to look at how it's used in the sentence.