A person who pretends not to notice wrongdoing or who secretly helps someone do something dishonest.
From Latin 'connivere' (to wink at, overlook) plus the agent suffix '-er' (one who). This forms the person-noun from the verb meaning to practice connivance.
A conniver is subtly different from a liar—they're complicit through silence rather than active deception. Shakespeare and crime novels love connivers because they're the enablers who make the central villain's actions possible.
Complete word intelligence in one call. Free tier — 50 lookups/day.