The word "glowered" means to stare intensely with anger or displeasure. There are a few synonyms for this word that can be used in writing to avoid repetition and add variety. One good synonym is "glared", which has a similar meaning but with a stronger emphasis on eye contact. Another option is "scowled", which implies a deep frown and a more menacing expression. "Frowned" is also an appropriate synonym for glowered, especially if the displeasure is more subtle. Lastly, "leered" can be used if the stare is more suggestive or inappropriate. All of these synonyms can be used effectively to add descriptive language and enhance the tone of a piece of writing.