Eclispe is 食 (しょく). Solar eclipse is 日食 (にっしょく) and lunar eclipse is 月食 (げっしょく).
Edit: Historically, 蝕 (しょく) was the Chinese character meaning "eclipse." It is still used by die-hard traditionalists like your sincerely but, alas, 食 has completely replaced it with regard to scientific terminologies.