• Unpopable,
• unpoppablel,
• unpoppabel,
• unpoppaable,
• unpoppabbel,
• unpopablle,
• upopable,
• unpoppoble,
• unpoppible

• unaffordable,
• unstoppable,
• unprovable,
• unbreakable,
• unthinkable,
• unbelievable,
• unpopular,
• unstaple,
• unflappable.

The adjective form of the word "unpoppable" is "unpoppable". This is a unique case where the adjective form is the same as the original word.

The plural form of "unpoppable" is still "unpoppable" as it is an adjective and does not change in the plural form.

The singular form of the word "unpoppable" is "unpoppable".