Synonyms for reluctant

Most common

1. Disinclined — not wanting to take some action; unwilling to do something

2. Hesitant

hesitant, diffident, slow, tardy, chary

Other

risk-averse, uneager, renitent, restiff

adj. 1
Not wanting to take some action; unwilling to do something.
She was reluctant to lend him the money
adj. 2
Tending to match as little text as possible.

From the opposite of reluctant, on the left, to its strongest synonyms, on the right.

Reluctant, Loath or Unwilling?

A man is loath to believe evil of his friend, reluctant to speak of it, absolutely unwilling to use it to his injury.

J. C. Fernald, English Synonyms and Antonyms (1914)

unwilling Tom seems to be unwilling to testify against Mary.
loath AI companies are loath to reveal their secret sauce.
reticent He is reticent and he never speaks unless spoken to.
disinclined I am not at all disinclined to have a glass of good wine.
hesitant I'm a little hesitant about going there by myself.
diffident Tom is such a diffident man. He seems to have quite low self-esteem.

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

The small number after each word is its number of syllables (tardy² = 2 syllables).