One of the tendons or nerves of the heart, or figuratively, one's deepest feelings and emotions.
From Old English 'heorte' (heart) + 'string' from Proto-Germanic 'strengiz'. Originally referred to anatomical structures, but by the 16th century became metaphorical for emotions, especially in the phrase 'pull at one's heartstrings.'
Medieval anatomists actually believed the heart had literal string-like structures controlling emotion, so when poets borrowed 'heartstrings' as metaphor, it felt scientifically grounded! This shows how poetic language often comes from genuine—if mistaken—observations about how bodies work.
Complete word intelligence in one call. Free tier — 50 lookups/day.