The h – [o] agá /ɐˈɡa/ – is a funny letter in Portuguese: we see it often, but we don’t bother pronouncing it (life is hard as it is, right?); that means anytime you see an h, you need to remember the letter for writing purposes but forget the h for its actual purposes.
It’s not as hard as it sounds, I promise.
#1: Since h is technically useless, why it is still used?
It is mostly a matter of convenience and history, allowing for the language to make explicit the connection to its forebears: when an h is indeed used, it marks Greek and Latin prefixes and words that were retained by the language somehow; since Old Portuguese lacked an h when silent (the exception being the forms of the verb haver, and that still exists today), it’s possible to conjecture that it reentered the Portuguese written language in the Late Middle Ages/start of the Renaissance, in which renewed interest in Classical Latin and Ancient Greek provided for changes in words from those languages to match their classical spelling (ex: LAT homo [hominem] > Old PT omẽe > Mod PT homem) and for the appearance of neologisms based on affixes from those languages.
#2: That said, h alone [that is, silent] is mainly found at the beginning of words – or the beginning of the second element of a hyphenated word that would take h anyway.
H can appear at the start of a word:
- In words that have Latin origins (or Greek, via Latin) or Latin expressions still in current use:
- A few borrowings from other languages that also use h (or that are transcribed with h):
- In Greek prefixes/radicals (changes vis-à-vis English noted when present)
- hagio- (related to saints)
- helio- (related to the sun)
- hemi- (half)
- hemo- (related to blood; English haemo-/hemo-)
- hidro- (related to water; English hydro-)
- hier(o)- (sacred)
- higro- (related to humidity, moisture, English hygro-)
- hiper- (higher, bigger, superior; English hyper-)
- hipo- (lower, smaller, inferior; English hypo-)
- hipo- (related to horses; English hippo-)
- hipno- (related to sleep; English hypno-)
- holo- (whole, entire)
- homo-, homeo- (the same, equal)
- hetero- (different)
- hexa- (six)
- hepta- (seven)
- In words where continued usage mandates its usage:
- húmido (humid)
- the interjections hum! (hmm!) hurra! (hurrah!)
H appears at the end of 1) a few interjections such as «ah!, eh!, óh!, ih!, pah!» ; 2) given names originating in Hebrew, when the h is pronounced (see link 1 given in this same paragraph).
#3: H doesn’t appear in many of the Portuguese version of Greek and Latin words where it is still retained in English.
These extra hs were removed from the language in the Spelling Reform of 1911, which tried to adjust the language’s orthography more closely to its phonology (i.e. the way people actually speak it). The list of changes goes as follows:
- (r)rh > r or rr, according to context; e.g.: rhizome > [o] rizoma; arrhythmia > [a] arritmia
- (p)ph (sound /f/)> f; e.g.: pharmacy (drug store) > [a] farmácia; sapphire > [a] safira
- ch (sound /k/) > c (before a, o, u, and consonants) / qu (before e and i); e.g.: chromatic > cromático/a; ischemia > [a] isquemia
- th (sounds /t/ or /θ/) > t (always /t/): theater > [o] teatro
- h at the start of a syllable inside a word: inhale > inalar; exhale > exalar; vehement > veemente
#4: A different usage of h – one independent from the process explained in rule #3, and that’s still in force – are its combination with c, l, and n to form three digraphs: ch, lh, and nh.
- CH represents the sound /ʃ/ (English sh)
- [a] chuva (rain): ʃˈu.vɐ
- [o] macho (male of a species): mˈa.ʃu
- [a] salsicha (sausage): saɫ.sˈi.ʃɐ
- LH represents the sound /ʎ/ (Spanish ll) – rarely starts a word
- [o] calhau (loose rock, stone, boulder): kɐ.ʎˈaw
- [a] palha (hay): pˈɐ.ʎɐ
- [o] telhado (roof): tɨ.ʎˈa.du
- NH represents the sound /ɲ/ (Spanish ñ, French gn) – rarely starts a word
- [a] doninha (skunk): dɔ.nˈi.ɲɐ
- [o] moinho (windwill): mwˈi.ɲu
- [a] vergonha (shame, embarrassment): vɨɾ.gˈo.ɲɐ