Boyd’s Bible Dictionary:
(desire). Rightful desire (1 Cor. 12:31, good). Wrongful desire, sinful (Ex. 20:17; 18:21; Prov. 28:16; Luke 12:15-34; 1 Tim. 6:9-10).
Concise Bible Dictionary:
In 1 Corinthians 12:31 and 1 Corinthians 14:39, the word is ζηλόω, and is quite different from the coveting that is condemned in scripture; it is translated in Revelation 3:19 “be zealous,” and the above passages in Corinthians can be so translated, or “desire earnestly” the best gifts, and “desire earnestly” to prophesy.