A person who detains or holds; a legal document or action preventing someone from leaving or a claim on property.
From detain + -er suffix (one who performs). Detain comes from Latin detinere (to hold back).
In immigration law, a detainer is an official order keeping someone in custody—it's a heavy word because it literally removes someone's freedom to move.
Complete word intelligence in one call. Free tier — 50 lookups/day.