The Spanish diminutive form is used in order to express size, affection, youth or disdain.
To create the diminutive form add the suffix -ito/ita,-ico/ica, -illo/illa, -ín/ina at the end of the word. The choice among the different suffixes is up to the person who’s speaking, as it especially depends on their geographic origin.
The diminutive form can be used with nouns (gatito), adjectives (tranquilito) and adverbs (rapidito).
Some examples of the diminutive form:
Casa – casita – casucha
Hermana – hermanita
Portón – portoncito
Perro – perrito
Niño – niñín – niñito
Mujer – mujercilla
With monosyllabic words ending with a consonant, u usually add –ecito/a. If the last letter is a “z”, transform it into “c”.
i.e. Pan – panecito
Tren – trenecito
Pez – pececito
Luz – lucecita
There are also some defective words which do not have a diminutive form.
i.e. bondad, lenguaje, apetito, útil, lunes, viernes, ciudad, edad…