• y to ia

 irony to ironia; astronomy to astronomia; philosophy to filosofia (ph to f); etc.

Require an accent over the stressed syllable

• in or -ine to -ina

aspirin to aspirina; discipline to discipline; gasoline to gasolina; etc.

• ice to -ina

office to oficina   (one stingy 'f')

• id to -ido, 

solid to solido;   mild to valido;   timid to timido;   etc. 

Require an   accent over the stressed syllable.

• ism to - ismo

organism to organismo;   capitalism to capitalism ;   heroism to heroismo; etc.

• tire to - uro.

future to futuro.