strikta

Tight first, strict second. Dictionaries put the physical sense at the front and they are right to: a strikta jacket is one that grips, and that is the sense a learner meets in ordinary prose. The abstract sense follows the same picture - a strikta rule leaves no slack - and it survives mainly in the fixed phrase en la strikta senco, in the strict sense, where the wording is being held tight around a single meaning.

For a strict person or a strict rule, reach for severa. This is the practical point of the page. English strict covers a stern teacher, a tight schedule and a narrow definition all at once, and the Esperanto word only really covers the third. The dictionary is unusually blunt about it and hands out a whole set of replacements: rigora where you mean precise, rigida for laws and conduct, mallarĝa or malvasta where you mean narrow, and streĉita for clothing that is pulled taut. Write severa patro, not strikta patro.

There is no suffix here. -ikt- is not an Esperanto affix and str- is not a root; strikt- is one borrowed unit, from a Latin participle that had already done its own joinery. Compare stringi, which Esperanto did not take, and the family is easier to see: to restrict is to draw tight again, a stringent rule draws tight, and a strain is what happens when you draw tight and something gives.

Derivations. Strikte (strictly, tightly), strikteco (tightness), striktigi (to tighten something), malstrikta (loose, slack). Do not confuse it with striko, a strike at work, which is a different root and a different word entirely.