Is there a word in Spanish which means "every two days"? If not, is there one which means "a period of two days" or "related to a period of two days"? By analogy to dial/diario, ..., triduano, cuatriduano.
There appear to be words referring to most other 'major' periods of time:
| 1/3 | 1/2 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | ... | 12 | ... | 15 | ... | 19
| DAY | | | dial | ... | triduano | cuatriduano | ... | ... | hebdomadario | ... | duodenario | ... | quincenal | ... | decemnovenal |
| WEEK | trisemanal | bisemanal | semanal | bisemanal | trisemanal | ... | ... | ... | ... | ... | ... | ... | ... |
| MONTH | trimensual | bimensual | mensual | bimestral | trimestral | cuatrimestral | ... | semestral | ... | ... | ... | ... | ... |
| YEAR | | bianual | anual | bienal | trienal | cuatrienal | quinquenal | sexenal | ... | ... | ... | ... | quindenial |
| DECADE| | | decenal | vicenal | tricenal | cuadricenal | ... | ... | ... | ... | ... | ... | ... |
If not, this appears to be a semantic gap in English as well, as the term for this is the phrase 'every other day'.