This doesn't mean ~という言葉.
強めて is acting adverbially. It's expressing the idea of "strengthening ..."
Similarly with からかって, it expresses the idea of "teasing" or "in jest".
I'm finding it hard to render this in English in a manner that bears some resemblance to the grammar of the Japanese.
Words that express a strong sense of being absorbed in love, or that are spoken in jest.
This might lead you to think you could shorten this to
But this loses the idea of "expression" and results in a rather strange definition, a definition that would somehow being claiming that the phrase 惚れた腫れた itself makes one more infatuated with someone. But that doesn't make sense.
By adding ていう, the editor of the dictionary is saying the phrase 惚れた腫れた expresses a strong sense of being caught up and lost in love.