Game: Words that end in -illa or -illo?
Today I made a Tortilla Española with my nephew.

I tried to explain that a torta is a cake in Spanish and I believe that the "illa" at the end denotes that it is in a round form. But, then, maybe it means small.
I started to think of other words that end in -illa or -illo...
anillo -- ring

bocadillo -- small bite -- snack (originally, filled roll).

So, am I right that -illa or -illo denote round shape?
No. I did some research and the -illo, -illa suffix is usually, but not always to denote the diminutive. Some stand alone words end with this suffix, words that do not denote smallness, so go figure. More commonly, the diminutive is denoted by -ito and -ita. Additionally, some regions of Spain and some Spanish-speaking countries go one way and some go another.
And, for the game...no need to keep it in alphabetical order, but let's post vocabulary words in Spanish that end in -illa or -illo, so that we can get familiar with them.
Because these are all nouns, add a picture if you like. It helps reinforce the learning for us visual learners.
42 Answers
toquilla headscarf
Sombrilla - parasol, sunshade
Borreguillo - Fleece
vajilla = tableware
1. Table-service of dishes, plates, etc. Vajilla de porcelana, Chinaware. (f)
* Lavar la vajilla -> to wash up

calzoncillo = underpants (slip) (British), shorts (United States); boxer shorts

Castillo= castle
Hey it's round at the top.
zapatilla - slipper, comfortable shoe
flequillo = fringe (British), bangs (United States)

Lazarillo (del Tormes) - a young boy who had lots of adventures and misfortunes.
Alfombrilla de ratón -- Mouse pad
el manilla:

- (dim.) Small hand. (m)
- Bracelet for the arm or wrist (pulsera). (m)
- Manacle, handcuff (de hierro). (m)
- Hand (de reloj). (m)
- Door handle. (Andes & Mexico) (m)
panecillo = bun or small loaf of bread; conejillo = bunny or small rabbit; canastilla = small basket ; manecilla = small hand ; bolsillo = pocket or small purse; banquillo = bench or little stool
Zarcillo - Earring
For the record, also: pendiente, arracada.
(Cuba y Méx.) Arete, aro, caravana.

Membrillo
- Quince-tree. (Botany) (m)
- Quince, the fruit of the quince-tree. (m)
- Quince jelly (m)

Mantequilla = butter