This article studies the semantic field of generic words for ‘stars’, ‘constella-tions’, and ‘planets’ in Early Irish. The Old Irish items discussed are: 1. the hapax ser, 2. rind, 3. the doubtful rét, 4. rétglu, 5. get, and 6. airndrethach. The items are subjected to a close semantic scrutiny, in order to modify the lexi-con definitions in cases where this is necessary. In addition, the etymologies of these words are discussed, which results in new or phonologically and morphologically more precise explanations for some of them. In Appendix 1, a potentially Proto-Celtic poetic formula involving a word for ‘star’ is reconstructed. Appendix 2 is concerned with Old Irish stíall*, a loan from Latin stella ‘star’, which only occurs in the name of the feast of the Epiphany.