The Esperanto Suffix -um: The Official Wildcard

-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.

-um on the internet: retumi

The web added one more: reto is a net, and the verb for browsing it is retumi.

• Mi retumis la tutan vesperon. - I browsed the web all evening.
• Mi foliumis la libron. - I leafed through the book.

Two words you need on any Esperanto website are built from ŝuti, to pour, with the prepositions el (out of) and al (towards). The pieces are regular, but the picture (pouring files) is convention, so learn them as a pair:

• Mi elŝutis la libron. - I downloaded the book.
• Ŝi alŝutis la foton. - She uploaded the photo.

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.

Action roots and thing roots

The second limit on derivation does not need -um- at all. Every root has a class before any ending touches it: an action (kombi, to comb), a thing (broso, a brush) or a quality (bona, good). The endings always make a grammatical word; what that word means depends on the class:

A comb and a brush sit on the same shelf, but their words were built in opposite directions. The action-root names the tool with -il-; the thing-root names the action with a plain -i:

• Mi kombas miajn harojn per kombilo. - I comb my hair with a comb.
• Mi brosas miajn dentojn. - I brush my teeth.

Nothing on the surface warns you. The dictionary form does: a dictionary lists kombi as a verb and broso as a noun, and that is the fact to carry.

The -o of an action-root names the act or its result, never the tool:

• Mi aĉetis ludilon por la infano. - I bought a toy for the child.

When a thing-root becomes a verb

A thing-root takes -i well only when the thing has one obvious action. A hammer has one job, so marteli is plain: to hammer.

• Li martelis la tutan matenon. - He hammered all morning.

A pencil writes, and skribi already says that, so the usual phrase is skribi per krajono. A table has no single action at all: verb it and nobody knows whether you mean laying it, sitting at it or building it. When a thing-root verb would leave your listener guessing, use a plain verb with per:

• Mi skribis per krajono. - I wrote with a pencil.

Mistakes English speakers make

What to do next

1. Learn the eleven -um- words in the table as vocabulary, with their roots beside them.
2. Say one sentence each with plenigi and plenumi.
3. Read compounding, the other way Esperanto builds words.

See also

• The affix system - the regular pieces this article is the exception to.
• Word endings - one root, four endings, and the root class behind them.
• igi and iĝi - the -ig- that makes malvarmigi compute.
• The tricky prepositions - je, the blank among prepositions.
• Compounding - building words from two roots.