Advisable means sensible and worth doing. Not compulsory — just clearly the better idea.
The word is impersonal by design, and it nearly always appears as it is advisable to, which recommends something without anybody taking responsibility for the advice. Guidance notes, insurance documents and travel warnings are full of it. It is a shade weaker than necessary and a shade stronger than a suggestion. The opposite, inadvisable, is the polite way of telling somebody their plan is a bad one.
1adjectiveadvisableSensible and worth doing.
“It is advisable to book well in advance.”
Proto-Indo-European
*weyd-
Middle English
avisen
English
advise
English, today
advisable
From advise + -able. advise comes from Middle English avisen. From Middle English avisen (“to perceive, consider, inform”), from Old French aviser, from avis, or from Latin advisō, from ad + visō. See also advice.
Etymology from Wiktionary, CC BY-SA