Bilateral symmetry— Mirror symmetry across a single axis. Fold the shape down its midline and the two halves match. The architecture of almost every animal body.Bitachon(Hebrew) — Trust, particularly in Hashem.Chokhmah(Hebrew) — Wisdom. In Chassidic thought, the source-level intelligence that precedes elaboration.D₆ (dihedral group)— The full symmetry group of a regular hexagon: six rotations and six reflections, twelve symmetries in all.Diffusion-limited aggregation— A growth process in which particles wander randomly and stick on contact, producing branching fractal patterns. Models lightning, river networks, and mineral dendrites.Fibonacci sequence— Named after Leonardo of Pisa (c. 1170–1250), known as Fibonacci. The numbers 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, … in which each term is the sum of the two before. Ratios of successive terms converge to φ.Fibonacci spiral— A piecewise quarter-circle spiral inscribed in a tiling of Fibonacci-numbered squares; the discrete approximation of the smooth golden spiral. See logarithmic spiral.Five-fold symmetry— Rotational symmetry of order 5; a turn of 72° maps the shape to itself. Found in flowers, sea urchins, and starfish; rare in minerals because regular pentagons cannot tile a plane. Also called pentaradial.Fractal— A pattern that repeats its structure at every scale. Coined by Benoît Mandelbrot in 1975 from the Latin fractus (broken).Fractal dimension— A measure of how completely a fractal fills space, falling between two integer dimensions. A coastline is ~1.25; lightning ~1.7; Romanesco broccoli ~2.66; the human lung surface ~2.97.Golden angle— 137.5° (= 360° ÷ φ²). The angle between successive seeds in a sunflower head; produces the densest non-overlapping packing.Golden ratio (φ)— The irrational number (1 + √5) ⁄ 2 ≈ 1.618. Two quantities are in golden ratio when the smaller is to the larger as the larger is to the sum.Hashem(Hebrew) — Literally "the Name." The customary way to refer to God in Torah-observant speech.Honeycomb Conjecture— The proposition that a regular hexagonal grid is the most efficient way to divide a plane into equal-area cells (least perimeter per unit area). Proved by Thomas Hales in 1999.Logarithmic spiral— A spiral whose radius grows by a constant factor with each turn — also called the equiangular spiral because every radius cuts the curve at the same angle. The nautilus shell, galaxy arms, and storm fronts all follow this curve.Murray's Law— In a branching vessel, the cube of the parent's radius equals the sum of the cubes of its branches' radii. Optimises flow in vascular networks, the lungs, and river systems.Panim el panim(Hebrew) — "Face to face." The closeness of divine encounter, as in Devarim 5:4.Phyllotaxis— The arrangement of leaves, seeds, or scales around a stem. Most plants follow a Fibonacci-based pattern set by the golden angle.Radial symmetry— Symmetry around a central axis or point; the shape repeats under rotation. Order n means a turn of 360° ⁄ n maps the shape to itself.Self-similarity— The property of a shape in which any part resembles the whole. The defining feature of fractals.Six-fold symmetry— Rotational symmetry of order 6; a 60° turn maps the shape to itself. Native to snowflakes and hexagonal lattices.Tensegrity— From "tensional integrity." A structural system held in shape by a balance of compression and continuous tension. Found in cell cytoskeletons, geodesic domes, and certain architectural structures.Tessellation— A tiling of a flat surface with no gaps or overlaps. Among regular polygons, only triangles, squares, and hexagons tessellate.Tiferet(Hebrew) — Beauty, splendour. In Kabbalah, the harmonising attribute between chesed (giving) and gevurah (restraint).Tzimtzum(Hebrew) — Divine contraction. The kabbalistic concept that Hashem "withdrew" to make space for creation.