What does subsequence mean?
In mathematics and computer science, a subsequence is an ordered selection from a longer sequence. It may omit elements, but the elements it retains keep their original order. Thus, for example, the letters “m,” “t,” and “s” occur in that order in “mathematics,” so “mts” is a subsequence even though the letters are not adjacent. The term is especially useful in combinatorics, sequence analysis, and computer science, where researchers search for patterns such as increasing subsequences or longest common subsequences. Unlike a substring, which must be contiguous, a subsequence may skip intervening items. In less technical prose, “subsequence” can also refer to a later or remaining portion of a sequence, though the mathematical and computing senses dominate. The word’s Latin ancestry is memorable: sub- suggests a secondary or following element, while sequi means “to follow.” Its combination makes it especially suitable for ideas involving order, selection, and partial continuity.
nounAn ordered selection from a longer sequence, formed by omitting some elements while preserving the order of those retained. More generally, it can mean a later or subsequent portion of a sequence.
- An ordered selection obtained from a longer sequence by deleting zero or more elements without changing the order of the remaining elements.
- A later or subsequent portion of a sequence.
"The sequence 3, 7, 2, 5 contains 3, 2, 5 as a subsequence."
"The letters m, t, and s occur in that order in “mathematics,” making “mts” a subsequence."
"The validator confirms that the query string is a subsequence of the allowed character list."
A subsequence is countable when it refers to a particular ordered selection; plural forms are especially common in mathematics and computer science.
"The algorithm efficiently finds all increasing subsequences of the input."
Keep the order, skip the stops: that is the whole trick of a subsequence.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does subsequence come from?
Subsequence was formed in English from the Latin-derived noun sequence and the Latin prefix sub-, meaning “under” or “secondary.” Sequence ultimately comes from Latin sequi, “to follow,” through the nounsequentia. Early mathematical usage applied the word to selections within a larger ordered sequence, and the term later became established in computer science for related operations on strings and other sequences.
Related word forms
How subsequence is actually used
The word is chiefly used in mathematics, computer science, and related technical fields. In general prose, its broader sense is relatively uncommon and may sound formal or abstract.
Easily confused with subsequence
A sequence is an ordered arrangement in full, whereas a subsequence is an ordered selection from it with some elements omitted.
A substring consists of consecutive elements, while a subsequence preserves order but may omit elements between the ones selected.