Bæddel ([ˈbæd.del]; BAD-dell) and bædling ([ˈbæd.liŋɡ]; BAD-ling) are Old English terms referring to non-normative sexual or gender categories. Occurring in a small number of medieval glossaries and penitentials, the exact meaning of the terms (and their distinction, if any) are debated by scholars. Both terms are often connected to effeminacy and adultery, although bæddel is defined as "hermaphrodite" in the two surviving glosses, while bædling is often glossed with terms associated with effeminacy and softness. The Oxford English Dictionary, citing the philologist Julius Zupitza, supports bæddel as the etymological root of the English adjective bad, although various scholars propose alternative origins, including a shared root with both bæddel and bædling.

The early medieval penitential Paenitentiale Theodori distinguishes men and bædlings as separate categories of person; it describes men having sex with other men or with bædlings as separate offences, and states that bædlings must atone for having sex with other bædlings. The term may have included people assigned female at birth who took on masculine social roles or referred to intersex people. Gender non-normative burials from the period have been associated with the term, and scholars have suggested that bædlings could represent a third gender outside the gender binary or a form of gender nonconformity in Anglo-Saxon society. The 11th century English Antwerp Glossary associates bæddel with the uniquely attested wæpenwifestre ([ˈwæːpnˌwiː.ves.tre] WAPN-wee-ves-tre), seemingly denoting a woman with a phallus or phallic masculinity.

Bæddel and bædling are Old English terms referring to some category of gender, sex, or sexuality outside the norm, although their precise meaning and scope are debated by scholars. While bæddel is associated with intersex people in the attested glosses, it also seems to connotate effeminacy. Bædling is thought by scholars to denote some sort of gender nonconformity, sexual passivity, or possibly a third gender. The terms are quite obscure; bædling is attested in a small number of sources—including two glossaries and two penitentials—while bæddel is only attested from two entries in the 11th century Antwerp Glossary. The linguist and etymologist Anatoly Liberman describes the terms as synonyms.

In the Antwerp Glossary, the word bæddel is used to gloss two Latin phrases: Andreporesis, i. homo utriusque generis ('andreporesis, i.e. man of both sexes') and Hermafroditus ('hermaphrodite'). The Antwerp Glossary associates bæddel with the otherwise unattested word wæpenwifestre. Literally a wif (woman) with a wæpn (weapon), it seemingly denotes a woman with a phallus or phallic masculinity along the lines of the common term wæpnedman (a male, lit. 'weapon-person').

Bædling is probably derived from bæddel, either with the patronymic suffix -ing or the diminutive patronymic suffix -ling. It is given three different Latin glosses in the four extant sources, including mollis 'soft person' and effeminati molles 'effeminate soft ones'. A third gloss from the Harley Glossary, cariar, is difficult to interpret and possibly a reference to the Anatolian region of Caria. Caria is the location of the legendary spring Salmacis, with the supposed power of feminising and softening men. The reference to Anatolia in the glossary may also indicate a connection with eunuchs, who were commonly associated with the Byzantine Empire and the Orient more broadly.

An Old English translation of the penitential handbook Paenitentiale Theodori makes a distinction between men and bædlings, describing "sex with other men" and "sex with bædlings" as separate (although equal) offences for men. It states that bædlings who have sex with other bædlings must atone for ten winters, describing them as "soft like an adulteress"; a similar comparison with adultery is also applied to bæddels in the Antwerp Glossary. The penitential also specifies that both adults and children can be bædlings, setting aside different punishments for bædlings of different ages. The historian Jacob Bell theorizes that the reference to a sexual relationship between two bædlings may refer to pederasty.

While in some of the extant sources bædling seems to have denoted a passive partner in gay sexual intercourse, the reference to bædlings having sex with each other complicates this as a strict definition. Indicated by an association in the Cleopatra Glossaries with the Latin mollis 'soft', they may have been people assigned male at birth who took feminine social roles or feminine gender presentation. It is debated by scholars how bæddels and bædlings fitted into the Anglo-Saxon gender system. Bædlings may be regarded as a third gender category outside of the bounds of manhood and womanhood, or as emasculated people who share a position of "non-manhood" with women and children when compared with "manly men". The term may have also referred to people assigned female at birth who took on masculine social roles, or (as with bæddel) to intersex people. The American philologist Robert D. Fulk has associated the terms with gender non-normative burials from the Anglo-Saxon period, including male skeletons buried alongside female grave goods.

During the late 19th and early 20th centuries, scholars such as J. R. C. Hall and Ferdinand Holthausen argued for an additional meaning of 'to defile' or 'to stain' for the Old English term bædan 'to compel', from which bæddel was possibly derived. They cite a Latin gloss in the 12th-century Eadwine Psalter. However, the psalter gives unusual and erroneous glosses for some Latin terms, causing philologists such as Herbert Dean Meritt (writing in 1954) to dismiss the alternate definition. Fulk, concurring with Meritt in 2004, derived bæddel from a hypothetical early Old English term *bai-daili-, 'both parts', mirroring the derivation of words for hermaphrodite in other Germanic languages, such as Danish tvetulle 'two tools'. A dialectal word badling attested in Northern England for variously 'rascal', 'worthless person', or 'naughty child', may descend from bædling, but could also be a later, independent derivation from bad and the suffix -ling. No reference is made to the word in the late Medieval period, but a 17th century Arthurian ballad in Scots mentions a Badlyng, a word which the scholar William Sayers identifies as "sodomite" in a 2019 paper.

The philologist Julius Zupitza theorized that the English word bad is derived from bæddel. James Murray, the first chief editor of the Oxford English Dictionary (OED), supported Zupitza's theory and included it in the dictionary's first edition in 1884. This etymology's inclusion in the OED led to widespread scholarly acceptance, although some philologists continued to contest it. The Oxford Dictionary of English Etymology more tentatively makes the connection, denoting it as only a possible etymology. The OED Online and the 1989 second edition of the Oxford English Dictionary continue to support Zupitza's theory, with the latter dismissing alternative etymologies from Celtic words as "out of the question", while also suggesting a possible origin from bædan.

Sayers proposes a shared etymology of bad, bæddel, and bædling from a reconstructed Gaulish word *baitos 'foolish, mad, immoral', an adjective carried into Old English by the hypothetical form *baed, which would connote shared "characteristics with the subaltern British". Writing in 1988, Richard Coates also describes bæddel and bædling as descended from a common ancestor with bad, in the form of a hypothetical Old English *badde possibly meaning 'worthless' or 'of ill omen'. Anatoly Liberman, concurring with Coates on the etymological link to *badde, states that bæddel was formed from bad. While yfel was the standard word for "bad" during the Old English period, bad was established enough by the thirteenth century to become a common nickname (in the form bade). The Dictionary of Old English gives no etymology for bædling, only tentatively defining it as "effeminate man" or "homosexual".

• Intersex people in history
• Homosexuality in medieval Europe
• Transgender history