# Technical term to describe/differentiate the structure of an instance by the number of samples per instance ('tuple' vs 'time series')

Several terms are used to describe the structure of instances of a dataset. For example, an instance can be 'univariate' if it depends on only one variable or 'multivariate' if it depends on 2 or more variables. I wonder if there are technical terms to distinguish the structure of a, let's call it a 'tuple', and a 'time series' or 'sequence'. Here are two examples that I am trying to describe or distinguish structurally: The left example is a time series, where all 11 samples belong to one instance. The right example is a collection of 'tuples' (if that is the correct term), where each row represents a separate instance.

I always refer to the term 'tuple' here, because the concept seems similar to me with the record in a database or the representation of points from mathematics. I am not sure if 'time series' and 'tuple' are the correct terms to describe how many samples an instance consists of. The terms should be analogous to uni/multivariate to describe the number of features in an instance.

Hence my question:
If univariate/multivariate describes an instance in the horizontal, what terms are used to describe an instance vertically?

We have a Dataset
Dataset has Instances

Instances can be a Vector Or a Sequence.

• If it is a vector,
It has Features
Examples - Image, Tabular data
• If it is a Sequence,
It has Time-steps**
Each Time-step can have Features i.e. Uni/Multi-Variate
Examples - Video, Audio, Time-series data

**When we use text-data as a sequence, we call the words as "Tokens"

• I conclude from the example with the image for the vectors that these are not only limited to 1-dimensional vectors, but can also be multi-dimensional (height x width x RGB channel) as in the case of colored images. Time steps, on the other hand, consist of a one-dimensional feature vector. Is that correct? Mar 19, 2021 at 11:24
• Time steps too can have multiple features e.g. If we measure Temperature, Pressure, Humidity from sensors. Similarly, think of video data. It's just has a temporal information across time steps. We can't shuffle the time steps randomly and make a sequence. Mar 19, 2021 at 15:08