résidus

Résidus is the plural of résidu in French and denotes substances that remain after a process, transformation, or measurement. It is a general term used across disciplines to describe leftovers, remnants, or new materials that persist after an operation. The precise sense depends on the field, ranging from physical matter to abstract quantities.

In waste management and environmental science, résidus refer to materials left over after production or consumption, such as household waste (résidus domestiques) or industrial residues (résidus industriels). They are categorized by hazard, potential for recycling or recovery, and environmental impact, and are subject to regulatory frameworks addressing handling, containment, and disposal.

In chemistry and food safety, résidus describe chemicals that persist after synthesis, processing, or application. This includes unreacted starting materials, by-products, and contaminant traces, such as pesticide residues on crops or drug residues in products. Regulation often specifies maximum residue limits and required testing to assess consumer exposure.

In mining and geology, résidus or mine residues refer to tailings and other materials remaining after ore extraction and processing. Proper management and containment are central to mitigating environmental risk and preventing contamination of soil and water.

In mathematics, résidus (residues) are the coefficients of the (z − z0)⁻¹ term in a function’s Laurent series, central to the residue theorem used to evaluate complex integrals.

In statistics, résidus (residuals) are the differences between observed values and those predicted by a model, used to diagnose model fit and identify anomalies. The term’s meaning is thus highly context-dependent, but always denotes what remains after a defined process.