To find the 21st term of the sequence $-3,2,7,\dots$, first determine the common difference of the arithmetic sequence.

1. Find the Common Difference:

$$\text{Common difference}=2-(-3)=5$$

2. Use the Formula for the $n$th Term of an Arithmetic Sequence:

$$a_n=a_1+(n-1)\cdot d$$

where $a_1$ is the first term, $d$ is the common difference, and $n$ is the term number.

For this sequence:
$$a_1=-3$$
$$d=5$$
$$n=21$$

3. Substitute the Values into the Formula:

$$a_{21}=-3+(21-1)\cdot 5$$
$$a_{21}=-3+20\cdot 5$$
$$a_{21}=-3+100$$
$$a_{21}=97$$

Thus, the 21st term of the sequence is 97.