plague Their first daughter died from the plague in 1576.
beset The company is still beset by technical challenges.
frustrate Tom secretly attempted to frustrate Mary's plans.
exasperate Sorry, I didn't mean to exasperate you with my endless questions.
confuse One should not confuse education with job training.

Popularity over time

Use in printed books, per decade from 1850 to 2019.

By length

3 letters: get¹, fox¹, bug¹, vex¹, irk¹
4 letters: rile¹, roil¹
5 letters: throw¹, devil², annoy², hound¹, beset²
6 letters: bother², puzzle², plague¹, harass², flurry², muddle², molest², baffle², pester², fuddle², bemuse²
7 letters: confuse², disturb², provoke², torment², bewitch², perplex², perturb², fluster², flummox²
8 letters: confound², entangle³, bewilder³, befuddle³, bodyjack
9 letters: frustrate², aggravate³, persecute³, tantalize³, tantalise
10 letters: exasperate⁴, disconcert³
14 letters: discombobulate⁵

The small number after each word is its number of syllables (devil² = 2 syllables).