Good examples of common gender nouns

Question

Some Latin nouns are common gender: their grammatical gender varies depending whether they refer to a male or a female (human or other animal). This is mentioned in many Latin grammars (including Allen and Greenough), and examples are often listed. However, I have never seen any proof in grammars that any of the listed words really behave this way. I don't really doubt that common gender nouns exist; I just found myself unable to very convincingly argue that they are a real thing in classical Latin.

To remedy this, I would like a couple of example words (two is enough), each word with two example passages from classical literature: one where it is feminine and another one where it is masculine. It would be great if the examples would be relatively simple and, most importantly, gender-wise unambiguous. Which example words and which passages would you suggest to demonstrate the existence of common gender nouns?

Notice that the question is not about all nouns with varying genders, but those nouns whose grammatical gender depends on the biological gender of the referent. This rules out words like dies and locus (with split plural loci/loca).

This question was inspired by an earlier question about feminine homo.

Answer 1

Bos, given in the previous answer, is a great example. Here are a few more:

• fur

  fures estis ambae. (Plaut. Poen. 5, 4, 67)

  M. Carbo condemnatus, fur magnus, e Sicilia... (Cic. Fam. 9, 21, 3)

• ales

  nocte deae Nocti cristatus caeditur ales (Ov. F. 1, 455)

  Lambere quae turpes prohibet tua prandia muscas,
  Alitis eximiae cauda superba fuit. (Mart. 14, 67)

• auctor

  Two great examples with separate genders in the same running passage:

  Dixit, et ut leges captis iustissimus auctor
  hostibus imposuit, classis retinacula solvi
  iussit et aeratas impelli remige puppes.
  Scylla freto postquam deductas nare carinas
  105nec praestare ducem sceleris sibi praemia vidit,
  consumptis precibus violentam transit in iram,
  intendensque manus, passis furibunda capillis,
  “quo fugis” exclamat, “meritorum auctore relicta,
  o patriae praelate meae, praelate parenti?” (Ov. Met. 8.101-109)

• civis

  num igitur aut fundos factos Veliensis, aut sacerdotem illam civem Romanam factam non esse, aut foedus et a senatu et a populo Romano violatum arbitramur? (Cic. Balb. 24.55)

More words: I won't include examples but can vouch that each has at least one citation in both genders in L&S:

• canis
• comes
• coniunx
• consors
• custos
• exsul
• grus
• heres
• hostis
• interpres
• iuvenis
• limax
• municeps
• nepos (with female referents: also later examples with explicit feminine modifier)
• pumilio
• quadrupes
• sodalis
• sus (both genders found in Varro)
• testis
• tigris

...And I'm sure there are many more, but I restricted this list to only words that I could explicitly verify.

Here are some cases where a noun has "different" genders, but more with regard to etymological circumstances or time period rather than the thing referred to:

• aer
• dies
• cinis
• corbis
• cupido

...and many more.

Answer 2

Bōs, bovis, m/f

This is the usual type of common-gender noun.

In the feminine, it means "cow".

Livy 1.7.6:

Inde cum actae boves quaedam ad desiderium, ut fit, relictarum mugissent, reddita inclusarum ex spelunca boum vox Herculem convertit.

(Heinemann trans)

As the cattle were being driven off, some of them lowed, as usually happens, missing those which had been left behind. They were answered with a low by the cattle shut up in the cave, and this made Hercules turn back.

In the masculine, it means "bull" or "ox".

Livy 25.12.13:

alterum senatus consultum factum est ut decemuiri sacrum Graeco ritu facerent hisce hostiis, Apollini boue aurato et capris duabus albis auratis, Latonae boue femina aurata.

(Heinemann trans)

A second decree was passed, that "the decemviri should perform sacrifice in the Grecian mode, and with the following victims: to Apollo, with a gilded ox, and two white goats gilded; to Latona, with a gilded heifer."

The masculine is considered "default" unless otherwise specified, hence the explicit addition of femina in the second passage.

Answer 3

Canis, canis, m/f

This is the archetypal common-gender noun, referring to a male or female dog.

Vergil, Georgics 1.469

Tempore quamquam illo tellus quoque et aequora ponti / obscenaeque canes inportunaeque volucres / signa dabant.

(Trans.)

At that particular time even the Earth itself, and the calm sea, and sinister dogs and ominous birds were giving signs.

Horace, Epodes 12.6

...quam canis acer ubi lateat sus.

(Trans.)

...like a perceptive dog [knows] where the sow might be hiding.