IPA: /səˌbsɪdiˈɛrɪti/
KK: /səbˈsɪdiˌɛrɪti/
The idea that decisions should be made as close to the local level as possible, rather than by a central authority, unless a higher level is more effective.
The principle of subsidiarity is important in ensuring that local governments have the power to make decisions that affect their communities.
Subsidiarity is formed from "sub-" (meaning under) and "sidiari" (from "sedeo", meaning to sit). The term refers to the principle that decisions should be made at the most local level possible, hence the idea of sitting under a higher authority only when necessary.
Think of decisions being made 'under' ('sub-') a higher authority, which helps you remember that subsidiarity means making choices at the most local level.