An Etymological Dictionary of Astronomy and Astrophysics

To grow together; to come together so as to form one whole, to fuse. → merge;
→ fusion.

Etymology (EN): From L. coalescere, from co- + al-, stem of alere “to nourish, make grow” + -esce, from -escere, a suffix conveying an inchoative meaning.

Etymology (PE): Âhamidan, from â- nuance prefix + ham “together” (Av. hama- “similar, the same;” Skt. samah “even, level, similar, identical;” Gk. hama “together with, at the same time,” homos “one and the same,” PIE *samos “same,” from base *sem- “one, together”) + -idan infinitive suffix.