The name Manmatha

कामशापानुग्रहो नाम तृतीयोऽध्याय

Kamadeva's curse alleviation Chapter 3

ऋषय उचुः |

Sages said (to Kamadeva)

यस्मात्प्रमथसे तत्त्वं जातोऽस्माकं यथा विधेः |

तस्मान्मन्मथनामा त्वं लोके ख्यातो भविष्यसि || 4 ||

Since you, born of the element of our Lord Brahma, will harass (all living beings), you will become known by the name Manmatha.

The next two lines say why he will also be called Kama and Kandarpa.