Rendaku (連濁^?, lit. "sequential voicing") is a phenomenon in Japanese morphophonology that governs the voicing of the initial consonant of the non-initial portion of a compound or prefixed word. In modern Japanese, Rendaku is common but unpredictable.^{[citation needed]}

Rendaku can be seen in the following:

In some cases, rendaku varies depending on syntax. For instance, the suffix 〜通り ("road, following"), from 通る tōru "to go, to follow", is pronounced as 〜とおり -tōri following the perfective verb tense, as in 思った通り omotta-tōri "as I thought", but is pronounced as 〜どおり -dōri (with rendaku) when following a noun, as in 予定通り yotei-dōri "as planned, according to schedule" (or, semantically differently – more concretely – 室町通 Muromachi-dōri, "Muromachi Street").

Research into defining the range of situations affected by rendaku has largely been limited to finding circumstances which cause the phenomenon not to manifest itself:

Lyman's Law states that rendaku does not occur if the second consonant of the second element is a voiced obstruent, a consonant sound formed by obstructing airflow. This was later modified to state that rendaku does not occur when the second element of the compound contains a voiced obstruent in any position (see third example below). This is considered to be one of the most fundamental of the rules governing rendaku.

Peter Engel (born 1959) is an American origami artist and theorist, science writer, graphic designer, and architect. He has written several books on Origami, including Origami from Angelfish to Zen, 10-Fold Origami: Fabulous Paperfolds You Can Make in Just 10 Steps!, and Origami Odyssey.

Engel studied the history and philosophy of science as an undergraduate at Harvard University, where he began studying origami seriously under design scientist Arthur Loeb. In 1987 he graduated from Columbia University with a master's degree in architecture.

Folding the Universe: Origami from Angelfish to Zen (1989) is his first book on origami. It is a highly unusual origami book in that besides the usual folding instructions, a significant portion was devoted to essays on the history of the craft as well as the theory. By exploring the relationship between art and science, and between creation, invention, and discovery, Engel provides unusual insights on the craft medium which has strict inherent constraints in favouring simple, geometric patterns and yet holds enough creative possibility within it to capture an unexpected range of complex forms. His models range from a unique coiled rattlesnake to a charming dollar bill bow tie to a delicate, detailed butterfly. The book also contains an interview with the legendary Japanese origami artist Akira Yoshizawa.