lend:  Lend and loan are closely related – come in fact from the same ultimate source (which also produced English delinquent, ellipse, and relinquish). Why then does the verb have a d while the noun does not? Originally there was no d. The Old English verb ‘lend’ was lǣnan, which in Middle English became lene. But gradually during the Middle English period the past form lende came to be reinterpreted as a present form, and by the 15th century it was established as the new infinitive. => delinquent, ellipse, loan, relinquish
late 14c., from Old English lænan "to lend," from læn "loan" (see loan). Cognate with Dutch lenen, Old High German lehanon, German lehnen, also verbs derived from nouns. Past tense form, with terminal -d, became the principal form in Middle English on analogy of bend, send, etc.