Why the word "sootikin" in a children's poem "Choosing Their Names"?

Question

In a poem entitled Choosing Their Names by Thomas Hood a stanza is:

One is black, with a frill of white,
And her feet are all white fur, too;
If you stroke her she carries her tail upright
And quickly begins to purr, too!
I think we shall call her this –
I think we shall call her that –
Now don’t you think that Sootikin
Is a nice name for a cat? 

When I googled sootikin it showed that sootkin is an awful word meaning deposit at women's vagina who do not wear underwear. I didn't find any other meaning except this. But I am sure it doesn't mean this at least here.

What does it mean? What is the opinion of a native speaker?

I found a question too in a 3rd grade book:

Why does the poet think sootikin is a suitable name for the cat?

Answer 1

I doubt that vulgar definition is relevant. It looks more like a combination of

Soot + i/y + kin

(See entries below.) In other words, Sootikin is simply a made-up cutesy, fanciful name based on the word soot, just like the other names in the poem: Pepperpot and Scratchaway. Similar made-up names would be Bestyboo, Mitchikins, etc.

Or more specific to these cats using i/y+kin:

• Pepperpot has emerald eyes: Greenikin
• Sootikin has white fur on her feet, and such cats are often named Socks: Socksikin
• Scratchaway is quarrelsome: Brawlikin

You can create a number of nicknames and pet names this way.

soot
noun
a black, carbonaceous substance produced during incomplete combustion of coal, wood, oil, etc., rising in fine particles and adhering to the sides of the chimney or pipe conveying the smoke: also conveyed in the atmosphere to other locations.
(Dictionary.com)

-y²
a noun-forming suffix with a variety of functions in contemporary English, added to monosyllabic bases to create words that are almost always informal. Its earliest use, probably still productive, was to form endearing or familiar names or common nouns from personal names, other nouns, and adjectives (Billy; Susie; birdie; doggie; granny; sweetie; tummy). The hypocoristic feature is absent in recent coinages, however, which are simply informal and sometimes pejorative (boonies; cabby; groupie; hippy; looie; Okie; preemie; preppy; rookie). Another function of -y2 (-ie ) is the formation from adjectives of nouns that denote exemplary or extreme instances of the quality named by the adjective (baddie; biggie; cheapie; toughie), sometimes focusing on a restricted, usually unfavorable sense of the adjective (sharpie; sickie; whitey). A few words in which the informal character of -y2 (-ie ) has been lost are now standard in formal written English (goalie; movie).
(Dictionary.com)

-kin noun suffix \ kən \
variants: or less commonly -kins \ kənz \
Definition of -kin (Entry 3 of 3)
: little
// catkin
// babykins
(M-W)

Answer 2

The ‘mouse-shaped deposit’ meaning is more properly linked to the word ‘souterkin’, meaning, per the OED

An imaginary kind of afterbirth formerly attributed to Dutch women

The earliest usage example in the OED is from 1658 and says:

There goes a Report of the Holland Women, that together with their Children, they are delivered of a Sooterkin, not unlike to a Rat, which some imagine to be the Off-spring of the Stoves.

And from 1862:

The housewives of Holland no longer bring forth sooterkins by sitting over the lighted chauffers.

The term, per the OED was also applied to people, specifically as a designation for the Dutch:

Ye Jacobites as sharp as Pins, Ye Mounsieurs, and ye Sooterkins, I'll teach you all the Dance.

But also applied to those of dark visage whether by occupation or nature:

The highwayman pushed poor Sooterkin [= chimney-sweep] out of the way.

And

Here is the sugar beside, which the hands of the sooterkin negro Reared [etc.].

Regarding the references to stoves and chauffers: in that period in the Netherlands women would have small ceramic stoves that they would tuck under their skirts when doing stationary work. Hence the idea that things under the skirts might get ‘sooty’.

This site explains and hosts paintings showcasing their use:

Foot stoves were used to warm the feet and were a common accessory in the Dutch household. The stoves were constructed with a wooden box that was ventilated on one side with holes or a slab at the top. Heat was conducted by burning charcoal that was placed in a ceramic or metal bowl (brazier) inside the stove. The feet were warmed by resting on top of the stove.

So, while the definition of ‘sootikin’ which abounds online is a slightly bastardised version of the original, it is possible that sootikin is being used in the transferred meaning of referring to the dark features of the cat.

The OED does offer another, obselete, and older definition, from the 1500s in Anglia, of ‘Sweetheart, mistress’ with an etymology of ‘older Dutch or Flemish *soetekijn < soet sweet.’

So possibly the use of ‘sootikin’ in the poem carries traces of this meaning also.

Answer 3

Sooty is often used as a name for black coloured pets, and -ikins is an affectionate diminutive ending. The other alleged 'meaning' does not make sense to any adult, and seems (from a brief Google search) to be mainly chuckled about by schoolboys. It also appears to be mentioned in a paper about internet trolling (paywalled).

Answer 4

Soetkin is an old Flemish name that goes at least as far back as the 1560s. Joseph Bernard Cannaert's Bydragen tot de kennis van het oude strafrecht in Vlaenderen, verrykt met vele tot dusverre onuitgegevene stukken ("Contributions to the knowledge of the old penal law in Flanders, enriched with many previously unpublished texts", 1835) cites a testament by a certain Soetkin van den Houte, who died in November 1560.

The name is still well known in Flanders today, especially because Charles De Coster named Till Eulenspiegel's mother Soetkin, i.e. in his 1867 novel La Légende et les Aventures héroïques, joyeuses et glorieuses d'Ulenspiegel et de Lamme Goedzak au pays de Flandres et ailleurs.[1]

Based on this, I hypothesise that Thomas Hood somehow picked up the name "Soetkin" (several decades before the publication of De Coster's novel) and turned it into Sootikin, possibly through the same type of folk etymology that can be seen in the other answers, which assume the name is based on the English words "soot" and "kin". Note that the Dutch or Flemish syllable "soet" is pronounced with the same ʊ as the English word "soot".

The Flemish name "Soetkin" is older than the earliest known occurrence of "souterkin" (according to the OED, cited in Spagirl's answer). It also predates John Maubray's work The Female Physician, which uses the word sooterkin.

[1] In the older German version attributed to Hermann Bote, Till's mother is called Ann Wibcken, so that work is not the source of the name "Soetkin".