1. Not proceeding by regular succession.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• ynsuccessive,
• hnsuccessive,
• jnsuccessive,
• insuccessive,
• 8nsuccessive,
• 7nsuccessive,
• ubsuccessive,
• umsuccessive,
• ujsuccessive,
• uhsuccessive,
• unauccessive,
• unzuccessive,
• unxuccessive,
• unduccessive,
• uneuccessive,
• unwuccessive,
• unsyccessive,
• unshccessive,
• unsjccessive,
• unsiccessive

• impressive,
• successive,
• aggressive,
• excessive,
• progressive,
• repressive,
• submissive,
• regressive,
• possessive,
• expressive.

The adjective form of the word "unsuccessive" is "unsuccessful".

The plural form of the word "unsuccessive" is "unsuccessives". However, it is worth noting that "unsuccessive" is not a commonly used word in English, so its plural form may not be widely recognized or used.

The singular form of the word "unsuccessive" is "unsuccess"