The English word "which" serves as an interrogative and relative pronoun used to specify one or more members of a defined set, often introducing clauses that provide additional information. Its etymology traces back to Old English, where it appeared as "hwilc" or "hwylc," meaning "which" or "what sort of." This Old English form is inherited from Proto-Germanic *hwalīkaz, a compound word that itself is constructed from two elements: *hwaz and *-līkaz.
The first component, *hwaz, is a Proto-Germanic interrogative pronoun meaning "who" or "what." This element ultimately derives from the Proto-Indo-European root *kʷó-, which functioned as an interrogative stem used in various forms to ask questions such as "who?" or "what?" This root is well-attested across Indo-European languages, appearing in Latin (quis), Ancient Greek (τίς, tís), and Sanskrit (कः, kaḥ), among others, demonstrating its fundamental role in forming interrogative pronouns.
The second component, *-līkaz, is a Proto-Germanic noun or adjective-forming element meaning "body," "form," or "appearance." This element is the ancestor of the English suffixes "-ly" and the word "like," both of which convey similarity or manner. The presence of *-līkaz in *hwalīkaz thus imparts a sense of "form" or "character" to the interrogative base. Consequently, the compound *hwalīkaz can be interpreted literally as "of what form" or "what-like," reflecting an inquiry into the nature, kind, or specific identity of something within a known set
This compound formation is not unique to English but is shared among other Germanic languages. For example, Old High German had "hwelih," which evolved into modern German "welch," and Old Dutch had "welc," which survives as Dutch "welk." These cognates demonstrate a common Proto-Germanic origin and similar morphological construction, combining the interrogative pronoun with the formative element indicating likeness or form.
In Old English, "hwilc" functioned both as an interrogative pronoun and as a relative pronoun, much as "which" does in Modern English. Over time, the initial "hw-" consonant cluster simplified to "wh-" in Middle English, and eventually to the modern spelling "which," though the pronunciation has varied regionally and historically. The retention of the "-ich" ending reflects the Old English adjectival inflection, which has largely been lost in contemporary usage.
It is important to distinguish this inherited Germanic formation from later borrowings or analogical formations. The word "which" is not a borrowing from Latin or Romance languages but rather a direct descendant of Proto-Germanic *hwalīkaz. Its components are inherited rather than borrowed, preserving a compound structure that is transparent in its original meaning but has become lexicalized in modern English.
The semantic development of "which" from a literal "what-like" to a pronoun specifying a subset within a known group illustrates a common pattern in the evolution of interrogative pronouns. Initially, the focus is on the form or nature of the referent, but this shifts toward selection and specification as the language develops more complex syntactic structures, such as relative clauses.
In summary, "which" originates from Old English "hwilc," itself derived from Proto-Germanic *hwalīkaz, a compound of the interrogative *hwaz ("who, what") and the formative *-līkaz ("body, form, appearance"). This etymology reveals that "which" fundamentally means "of what form" or "what-like," a meaning that aligns closely with its modern function of asking for specification within a set. Its cognates in German and Dutch attest to a shared Germanic heritage, and its components trace back to the Proto-Indo-European interrogative root *kʷó- and the Proto-Germanic formative *līkaz. There is no evidence of borrowing