The description of the word you requested from the astronomical dictionary is given below.
The year is a period of time that is related to the motion of the Earth around the Sun. There are quite a few different kinds of years in use:
For the four cardinal directions along the ecliptic, tied to the beginning of the four seasons, the tropical years are on average as shown in the following table. In this table, the "length" is the corresponding ecliptic longitude, "month" the month in the Gregorian calendar when the Sun reaches the cardinal direction, "year" the length of the corresponding tropical year, "change" the rate of change in the length, and "name" a name that I propose for this type of year.
Sometimes, tropical year is used for the average over all positions along the ecliptic (the average over all seasons). We can call that the "average tropical year", though that is still ambiguous. Do you mean averaged over all positions along the ecliptic (for one or more elapsed years), or averaged over a number of years (for one position along the ecliptic)? For more distinction, we could call the first kind the "ecliptic-averaged tropical year", and the second the "time-averaged tropical year" (but we should then also specify the associated position along the ecliptic, e.g., the "time-averaged northern-solstice year").
It is clear that "tropical year" by itself is too vague. If the difference between all of the subtypes is important to you, then you should explain very clearly exactly which kind of tropical year you mean.