On a previous quesetion I was corrected for having written 'Ele visita a instituicoe', saying that the correct spelling of 'institution' is 'instituicao'. Was that a glitch or is there some rule as to how to spell 'institution'? Thanks.
instituição is sigular, instituições, plural. The plural for words ended in -ção can be -çãos/ções.
And çães. But no rules.
Capitão - Capitães (captain)
Cão - Cães (dog)
Avião - Aviões (Plane)
Mão - Mãos (hands)
One institution is "instituição", and the plural is "instituições". There are a few different ways to pluralize words that end in -ão, and I'm not sure if there are rules to tell you which one to use, or if you just have to memorize the correct plural for each word. Anyway, this page will help you: http://www.easyportuguese.com/Portuguese-Lessons/Plural.html