Valmiki Ramayana 7.12.2
स्वसारं कालकेयाय दानवेन्द्राय राक्षसीम् ।ददौ शूर्पणखां नाम विद्युज्जिह्वाय नामतः॥
svasāraṃ kālakeyāya dānavendrāya rākṣasīm |dadau śūrpaṇakhāṃ nāma vidyujjihvāya nāmataḥ ||
Our plain-language meaning of this verse is waiting for scholar review.
Open in the book