Origins
The word 'arrow' has a deceptively simple appearance that conceals a rich etymological journey and a surprising family of relatives. It descends from Old English 'earh' (arrow), from Proto-Germanic *arhwō, from PIE *h₂érkʷo- (bow, arrow). The same PIE root produced Latin 'arcus' (bow, arc), which entered English through French as 'arc,' 'arch,' and 'arcade.' This means that 'arrow,' 'arc,' 'arch,' 'arcade,' and 'archery' are all descendants of the same ancient word for the bow — one of the oldest and most consequential human weapons.
The semantic relationship is illuminating: the arrow was named not as an independent object but as 'the thing that belongs to the bow' — defined by its relationship to the weapon that propels it. Latin took the same root and focused on the bow's shape — the curve — giving rise to 'arcus' and all its architectural and geometric descendants. Two branches of the same family, one emphasizing the projectile, the other the curve.
The morphological history of 'arrow' in English is unusual. Old English 'earh' was a short, monosyllabic word. During the Middle English period, it acquired an additional syllable, becoming 'arwe' and then 'arowe.' This expansion likely occurred through the reanalysis of an oblique case form — the Old English genitive/dative forms 'earwes/earwe' were reinterpreted as containing a stem 'arw-' to which the nominative ending '-e' (later '-ow') was added. The result is that Modern English 'arrow' is morphologically larger than its Old English ancestor, an unusual development since English words typically shrink over time.
Proto-Indo-European Roots
In Old English, 'earh' was not the only word for arrow. 'Flā' (related to 'fledge' and 'fly' — the feathered thing that flies) was also used, and the two words coexisted. 'Flā' eventually fell out of use, surviving only in the compound 'flan' as borrowed into French ('flèche' is from Frankish *fliukka, a different word). The Old Norse cognate 'ǫr' (arrow) also comes from the same Proto-Germanic root.
The arrow has enormous symbolic weight across cultures. In Greek mythology, Eros's arrows cause love; in Christian iconography, Saint Sebastian is pierced by arrows; in English idiom, 'the slings and arrows of outrageous fortune' (Shakespeare, Hamlet) uses arrows as a metonym for affliction. The arrow symbol (→) in typography and mathematics derives from the physical object, and the modern 'cursor arrow' on computer screens preserves the ancient image in digital form.
The phrase 'straight as an arrow' dates from at least the sixteenth century. 'Arrow' as a directional indicator — signs, road markings, user interface elements — represents one of the longest conceptual transfers from weapon to abstract symbol in human history.