In general, the term "wave" can refer to both a single complete cycle of a wave and to multiple cycles of waves. The interpretation depends on the context in which the term is used.
When discussing a single complete cycle of a wave, it is often referred to as a "waveform" or an "oscillation." In this context, a wave represents the pattern of disturbance or oscillation as it repeats over time or space. For example, in the case of a sine wave, a single complete cycle refers to the wave going from its peak to its trough and back to its peak.
On the other hand, when multiple cycles of waves are referred to as "a wave," it usually means a collection of individual cycles that share similar characteristics. This usage is commonly encountered when dealing with waves in the physical world, such as ocean waves, sound waves, or electromagnetic waves. In these cases, a wave represents a sequence of repeating patterns or oscillations.
To summarize, "a wave" can refer to either a single complete cycle of a wave or to multiple cycles of waves, depending on the specific context in which the term is used.