penny n.

English coin, Middle English peni, from Old English pening, penig, Northumbrian penning "penny," from Proto-Germanic *panninga- (source also of Old Norse penningr, Swedish pänning, Danish penge, Old Frisian panning, Old Saxon pending, Middle Dutch pennic, Dutch penning, Old High German pfenning, German Pfennig, not recorded in Gothic where skatts is used instead), a word of unknown origin.

Offa's reformed coinage on light, broad flans is likely to have begun c.760-5 in London, with an awareness of developments in Francia and East Anglia. ... The broad flan penny established by Offa remained the principal denomination, with only minor changes, until the fourteenth century. [Anna Gannon, "The Iconography of Early Anglo-Saxon Coinage," Oxford, 2003]

The English coin was originally set at one-twelfth of a shilling (or 240 to a Tower pound) and was of silver, later copper, then bronze. There are two plural forms: pennies of individual coins, pence collectively. In Middle English, any coin could be called a penny, and in translations it rendered various foreign coins of small denomination, especially Latin denarius, whence comes its abbreviation d.

As an American English colloquial for cent, it is recorded by 1889. In reference to nails, "a pound," denoting that 1,000 nails will weigh so much, OED says it probably is based originally on the price per 100 and persisted as prices fell.

Penny-a-liner "writer for a journal or newspaper" is attested by 1830, from their supposed rate of pay. Penny dreadful in reference to "cheap and gory fiction" dates from 1870. Phrase penny-wise and pound-foolish is recorded from c. 1600.

Penny-pincher "miserly person" is recorded from 1906 (Middle English had pinchpenny (n.) in that sense; as an adjective penny-pinching is recorded from 1858, American English). Penny loafers attested from 1960, perhaps from the fashion of slipping a penny into the slits of the bands across the facing.

"A regular penny-a-liner is a person who supplies the newspapers of the city with short articles of news, ingenious remarks upon the current topics of the day, reports of meetings, or of cases in the police offices, accidents, &c. &c., but who, observe, has no express engagement from, or any direct connexion with, any newspaper whatever. His success is wholly precarious—always uncertain. If the contributions which those persons forward for publication, in this way, are published, they are certain of payment for them at the rate of one penny, three half-pence, and in rare cases, two pence a-line, according to the importance of the subject matter supplied. ["The London Penny-a-Line System," Irish Monthly Magazine, January 1833]