Final answer:
The 5-letter word for gleaming brightness or luster is 'gleam,' which fits the definition and letter count.
Step-by-step explanation:
5-Letter Word for Gleaming Brightness or Luster
The 5-letter word for gleaming brightness or luster is gleam. This word fits both the definition and the required letter count. The options provided were a) Shine, b) Gleam, c) Spark, d) Glint. While 'shine', 'spark', and 'glint' are related to light or brightness, 'gleam' specifically captures the essence of gleaming brightness or luster in a concise 5-letter word.