Modifiers matching duck:

• jealous,
• slobbery,
• rare,
• tenacious,
• large,
• optimistic,
• native,
• boastful,
• paranoid,
• bullying,
• common,
• breeding,
• indigenous,
• daffy,
• insecure,
• short-tempered,
• lisping,
• here,
• smaller,
• small,
• wild,
• brash,
• zany,
• determined,
• aggressive,
• domestic,
• pushy,
• marine,
• larger,
• unusual,

Simple categories matching optimistic:

• child,
• invalid,
• lawyer,
• writer,
• person,
• lover,
• poet,
• scholar,
• billionaire,
• guru,
• clown,
• soldier,
• shyster,
• philosopher,
• hero,
• duck,
• boxer,
• director,
• sidekick,
• warrior,
• politician,