In cryptography, FROG is a block cipher authored by Georgoudis, Leroux and Chaves. The algorithm can work with any block size between 8 and 128 bytes, and supports key sizes between 5 and 125 bytes. The algorithm consists of 8 rounds and has a very complicated key schedule.

Frogs are a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura (Ancient Greek an-, without + oura, tail). The oldest fossil "proto-frog" appeared in the early Triassic of Madagascar, but molecular clock dating suggests their origins may extend further back to the Permian, 265 million years ago. Frogs are widely distributed, ranging from the tropics to subarctic regions, but the greatest concentration of species diversity is found in tropical rainforests. There are approximately 4,800 recorded species, accounting for over 85% of extant amphibian species. They are also one of the five most diverse vertebrate orders.

Frog is an album by the Japanese noise musician Merzbow. It was inspired by frogs and utilizes their sounds. Masami Akita exhibited the audio and images at Yokohama Triennale 2001 in an installation called . It was reissued on CD in 2002, retitled Frog+, with a bonus disc of additional material and a screensaver.

Frug is a surname; The Polish-Jewish spelling: Fróg. Other transliterations include Frog, Phroog.