Modifiers matching grump:

• fastidious,
• wealthy,
• grouchy,
• principled,
• covetous,
• ill-tempered,
• miserly,
• heartless,
• rich,
• impatient,
• misanthropic,
• condescending,
• gruff,
• arrogant,
• mean,
• jealous,
• penny-pinching,
• grizzled,
• greedy,

Simple categories matching ill-tempered:

• person,
• grump,
• tyrant,