Strict

1. Strained; drawn close; Tight.
2. Tense; not relaxed.
3. Exact; Accurate; Precise; rigorously particular.
4. Governed or governing by exact rules; observing exact rules; Severe; Rigorous.
5. Rigidly interpreted; exactly limited; Confined; Restricted.
6. (botany) Upright, or straight and narrow; — said of the shape of the plants or their flower clusters.
7. Severe in discipline. Antonyms: lenient, lax, permissive
8. (set theory, order theory) Irreflexive; if the described object is defined to be reflexive, that condition is overridden and replaced with irreflexive.

Usage notes

• Stricter and strictest are the grammatically correct forms for the comparative and superlative though outside the UK more strict and most strict are more often used.