singly

Singly is an adverb meaning one at a time or individually. It emphasizes that items or actions are dealt with separately rather than collectively. In everyday usage, singly is somewhat formal; speakers typically prefer phrases like one at a time in casual contexts.

The word is formed from the adjective single with the adverb suffix -ly. It has appeared in English since the Middle English period and remains more common in formal, scientific, or technical writing today.

In computing, singly appears in the term singly linked list, a data structure in which each element contains a single link to the next element. This contrasts with doubly linked lists, where nodes point to both the next and previous elements, enabling traversal in either direction.

In science and mathematics, singly describes states with a unit charge. In chemistry and physics, singly ionized refers to an ion with a net charge of +1 or -1, such as H+ or Na+. In spectroscopy and plasma physics, singly ionized species are common in hot environments and emit characteristic lines that help identify composition and conditions.

Beyond technical contexts, singly can be used to denote actions performed individually or separately, though many writers prefer clearer phrases like individually or one by one. The term remains grammatically valid and is understood across English dialects, especially where precision or conciseness is required.