The -um wildcard: convention, not computation

-um- is the one Esperanto suffix with no fixed meaning. It says a word has something to do with its root and leaves the rest to usage. So kolumo (a collar), brakumi (to hug) and malvarmumi (to catch a cold) are words to learn, not words to work out.

-um: the suffix that guarantees nothing

Every regular affix computes. Meet a new word built from one and you can work out what it means:

-um- does not. The Fundamento's dictionary gives it no set meaning, and it plays the same role among suffixes as je among prepositions: the official blank.

The words you will meet most:

• Ŝi brakumis sian patrinon. - She hugged her mother.
• Mi akvumas la florojn. - I am watering the flowers.
• Venis proksimume cent homoj. - About a hundred people came.

Read down the Meaning column and you will find no thread. The root gives you the neighbourhood (something to do with the neck, something to do with air); usage picked the house.

Convention or computation: malvarmumi and malvarmigi

The pairs to keep apart share a root and differ only in the suffix. The regular one says what it does; the -um- one you must know:

• Mi malvarmigis la supon. - I cooled the soup.
• Mi malvarmumis. - I caught a cold.
• Ŝi plenigis la glason. - She filled the glass.
• Ŝi plenumis sian promeson. - She kept her promise.

Malvarmumi takes no object: you catch a cold, you do not cold anything. Put an object after it and you have the wrong word.

Do not coin new -um words

A regular word is understood the first time you meet it, because the affix computes. A new -um- word computes to nothing:

So coin freely with -ej-, -il-, -ig- and the rest, and treat -um- as a list you learn, not a pattern you extend: the few newcomers, like retumi, caught on because a whole community adopted them. When no regular word fits, say it with a phrase: skribi per krajono, to write with a pencil.