Underdrawing is a preparatory drawing done on a painting ground before paint is applied, for example, an imprimatura or an underpainting. Underdrawing was used extensively by 15th century painters like Jan van Eyck and Rogier van der Weyden. These artists "underdrew" with a brush, using hatching strokes for shading, using water-based black paint, before underpainting and overpainting with oils. Cennino D'Andrea Cennini (14th century most likely) describes a different type of underdrawing, made with graded tones rather than hatching, for egg tempera.
In genetics, underdominance (referred to in some texts as "negative overdominance" ) is the opposite of overdominance. It is the selection against the heterozygote, causing disruptive selection and divergent genotypes. Underdominance exists in situations where the heterozygotic genotype is inferior in fitness to either the dominant or recessive homozygotic genotype. Compared to examples of overdominance in actual populations, underdominance is considered more unstable and may lead to the fixation of either allele.
Underrail is a turn based role-playing video game developed and published by Stygian Software for Microsoft Windows. It was made available as an early access title in late 2012, and was officially released in December 2015. An expansion, titled Expedition, was released in July 2019.