Ineptitude implies a critical assessment of someone's abilities, often seen as an insult. The manager's ineptitude meant he couldn't lead the team effectively.
Pro Tip 2/3
Situational Use
Use 'ineptitude' to refer to specific situations where someone shows lack of skill, not general intelligence. Despite his math ineptitude, he is a brilliant writer.
Pro Tip 3/3
Not Inherent
'Ineptitude' often implies a temporary state, suggesting improvement is possible. Her cooking ineptitude lessened with practice.