malstreĉiĝi

Four pieces, and every one of them earns its place. Take it apart from the inside out.

Streĉ- is tension. Streĉi is to pull something taut: a violin string, a bow, a clock spring, your own shoulders. Add mal-, which reverses, and malstreĉi is to slacken it off - still transitive, still something you do to a thing. Then add -iĝ-, which turns the action inward so that nobody is doing it any more, and the thing simply goes into that state. Malstreĉiĝi: to come loose, to slacken, to relax. Then -i, the infinitive.

mal- + streĉ + -iĝ- + -i. Prefix, root, suffix, ending, in that order, and you can read the meaning straight off the page without ever having seen the word.

The superlative nobody else can claim. Of the fifty mal- words this course has taught, malstreĉiĝi is the only one that also carries -iĝ-. It is the single place where the prefix that flips the meaning and the suffix that flips the grammar land on the same root, and that makes it the best worked example in the whole affix system: two machines, one word, no irregularity anywhere. (It is not the longest - malmultekosta, inexpensive, runs to five pieces - but it is the most instructive.)

Get the transitivity right, because this is where learners fall over.

• Streĉi - to tighten something. Mi streĉas la ŝnuron.
• Malstreĉi - to loosen something. Mi malstreĉas la ŝnuron.
• Streĉiĝi - to become tense, by itself. La ŝnuro streĉiĝas.
• Malstreĉiĝi - to become slack, to relax. La ŝnuro malstreĉiĝas.

The -iĝ- verbs take no object, ever. If you catch yourself writing malstreĉiĝi la muskolojn you have wanted malstreĉi. The igi and iĝi article is the one to read if that still feels slippery; it is the most useful pair of suffixes in the language and English hides the distinction entirely.

Against the neighbours. Ripozi is to rest, to stop doing the work, and it says nothing about tension. Trankvila is the adjective for calm. Malstreĉiĝi is specifically the tension going out - which is why it works equally well for a muscle, a rope and a political situation. Malstreĉiĝo is the noun, and in the language of diplomacy it is exactly what French calls détente.