From siom (“disappointment”) + -i.
siomi (first-person singular present siomaf, not mutable)
| singular | plural | impersonal | ||||||
|---|---|---|---|---|---|---|---|---|
| first | second | third | first | second | third | |||
| present indicative/future | siomaf | siomi | sioma | siomwn | siomwch | siomant | siomir | |
| imperfect (indicative/subjunctive)/ conditional |
siomwn | siomit | siomai | siomem | siomech | sioment | siomid | |
| preterite | siomais | siomaist | siomodd | siomasom | siomasoch | siomasant | siomwyd | |
| pluperfect | siomaswn | siomasit | siomasai | siomasem | siomasech | siomasent | siomasid, siomesid | |
| present subjunctive | siomwyf | siomych | siomo | siomom | siomoch | siomont | siomer | |
| imperative | — | sioma | siomed | siomwn | siomwch | sioment | siomer | |
| verbal noun | siomi | |||||||
| verbal adjectives | siomedig siomadwy | |||||||
| Inflected colloquial forms | singular | plural | ||||
|---|---|---|---|---|---|---|
| first | second | third | first | second | third | |
| future | sioma i, siomaf i | siomi di | siomith o/e/hi, siomiff e/hi | siomwn ni | siomwch chi | sioman nhw |
| conditional | siomwn i, siomswn i | siomet ti, siomset ti | siomai fo/fe/hi, siomsai fo/fe/hi | siomen ni, siomsen ni | siomech chi, siomsech chi | siomen nhw, siomsen nhw |
| preterite | siomais i, siomes i | siomaist ti, siomest ti | siomodd o/e/hi | siomon ni | siomoch chi | siomon nhw |
| imperative | — | sioma | — | — | siomwch | — |
| Note: All other forms are periphrastic, as usual in colloquial Welsh. | ||||||