Origins
The verb 'lend' is the natural counterpart of 'borrow,' but the two words come from entirely different roots and embody different conceptual frameworks for the same transaction. While 'borrow' derives from a root meaning 'to pledge,' 'lend' descends from a root meaning 'to leave' — reflecting the lender's perspective that they are leaving their property in someone else's hands.
The Old English form was 'lǣnan,' a weak verb meaning 'to lend, grant, lease.' It was derived from the noun 'lǣn,' meaning 'a loan, gift, grant, benefit, thing lent,' which came from Proto-Germanic *laihwniz. The related Gothic form 'leiƕan' (a strong verb meaning 'to lend') confirms the antiquity of the root in Germanic. The Proto-Germanic forms trace back to the PIE root *leykʷ-, meaning 'to leave, to remain behind,' which also produced Greek 'leipein' (to leave), Latin 'linquere' (to leave, abandon — source of English 'relinquish' and 'delinquent'), and Sanskrit 'riṇákti' (to leave).
The semantic connection between 'leaving' and 'lending' is intuitive: when you lend something, you leave it in another person's possession. The same conceptual link appears independently in other language families, suggesting that the metaphor of lending-as-leaving is a natural one for human cognition. The noun 'loan,' which entered English from Old Norse 'lán,' is a close relative from the same Proto-Germanic source, *laihwnō.
Old English Period
The modern form 'lend' requires explanation, since Old English 'lǣnan' had no final '-d.' The addition of this consonant occurred during the Middle English period, probably by analogy with other common verbs ending in '-nd': 'send,' 'bend,' 'rend,' 'wend.' This analogical process — where a word acquires a sound it never historically had because speakers unconsciously pattern it after similar-sounding words — is surprisingly common in English. The same mechanism added a '-d' to 'sound' (from Old French 'son') and 'bound' (in the sense 'ready to go,' from Old Norse 'búinn').
Like its counterpart 'borrow,' Old English 'lǣnan' had some bidirectional quality — it could occasionally mean 'to grant' more generally, and the noun 'lǣn' could mean 'a gift' as well as 'a loan.' The Anglo-Saxon theological concept of life as a 'lǣn' from God — a temporary grant that must eventually be returned — appears repeatedly in Old English poetry. In 'Beowulf,' earthly possessions and even life itself are described as loans from the Almighty, reflecting a worldview in which nothing is truly owned, only temporarily held.
The Germanic cognates show the same range of meanings. German 'leihen' means both 'to lend' and 'to borrow' (though 'ausleihen' and 'entleihen' can disambiguate). Dutch 'lenen' is similarly bidirectional. Old Norse 'lána' meant 'to lend' or 'to grant on loan.' This pattern of a single verb covering both sides of a lending transaction — shared with 'borrow/borgian' — suggests that early Germanic speakers conceptualized lending and borrowing as a unified social act rather than two distinct actions.
Later Development
The past tense 'lent' shows the regular weak verb pattern (compare 'send/sent,' 'bend/bent'), with the voicing assimilation of the dental suffix to the preceding nasal. This past tense form is itself the source of the Christian season of 'Lent,' though by a different route: Old English 'lencten' meant 'spring' (literally 'the lengthening' of days) and was applied to the pre-Easter fasting period because it falls in spring. The homophony with 'lent' (past tense of 'lend') is coincidental.
In modern English, 'lend' has developed numerous figurative uses. 'To lend a hand' (to help) treats assistance as something temporarily granted. 'To lend an ear' (to listen attentively) dates from Shakespeare. 'To lend credence' or 'lend weight to' treats abstract qualities as transferable property. 'To lend itself to' (to be suitable for) is a reflexive construction implying that a thing voluntarily makes itself available.
The financial derivative 'lender' has become a loaded term in modern economics. 'Lender of last resort' (the central bank function of providing liquidity in a crisis) was first articulated by Walter Bagehot in 1873. 'Predatory lending' describes exploitative loan practices. The 2008 financial crisis put 'subprime lending' into the global vocabulary. Through all these developments, the word continues to carry the implication embedded in its PIE root: when you lend, you leave something in another's hands, trusting that it will come back.