In strict music terminology, a song is usually defined as a piece of music that always includes which essential element?

Introduction / Context:
This question comes from basic music terminology and tests how precisely you understand the word "song". In casual everyday speech, people sometimes call any piece of music a song, even if it has no words. However, in more careful usage and in many exams, the term has a narrower, clearer meaning. Recognising that difference helps you answer this question correctly.

Given Data / Assumptions:
- The question talks about "strict music terminology".
- We have to choose the element that a song always includes by definition.
- Options include a musician, a tymbal, words or lyrics, a chorus, and an orchestra.

Concept / Approach:
In music theory and traditional usage, a "song" is a vocal composition that combines music with words. The key idea is that a song is meant to be sung. If a piece is purely instrumental, many musicians will call it a "piece", "composition", or "instrumental track", not a song. Therefore, the defining element that must be present is words or lyrics. Other elements, such as musicians, instruments, or a chorus, are common but not essential in every case.

Step-by-Step Solution:
Step 1: Concentrate on the phrase "always includes", which means the element must be present in every example of a song in the strict sense.
Step 2: Notice that some songs are performed by only one singer and one instrument, so neither an orchestra nor a chorus is truly essential.
Step 3: Understand that musicians are always needed to perform, but a "song" as a composition is defined by its structure, not by how many people perform it.
Step 4: Recognise that words or lyrics are the core feature that separates songs from purely instrumental pieces, so they are the essential element.

Verification / Alternative check:
Imagine different examples: a folk singer alone with a guitar, a pop singer using a backing track, a choir singing a hymn, and a child singing a nursery rhyme. All of these have words. Now think of a piano solo or a violin concerto; these are well known musical works but are not called songs in strict terminology because they have no lyrics. This contrast confirms that words or lyrics are what a composition must include to be classed as a song.

Why Other Options Are Wrong:
- a musician: necessary for performance, but a song as a composition can exist even before anyone performs it.
- a tymbal: a specific instrument, not present in most songs.
- a chorus: common in many songs but not present in every song, for example, some traditional ballads and art songs have no repeating chorus.
- an orchestra: many songs use only a single instrument or a small band, not a full orchestra.

Common Pitfalls:
Because people casually say "listen to this song" for any track, it is easy to forget the stricter definition. In exam situations, always assume that technical terms are being used carefully. When you see a question about "song" and "always", think of lyrics and singing rather than any kind of instrumental track.

Final Answer:
In strict usage, a song always includes words or lyrics.