diff --git a/node-health/src/readiness.ts b/node-health/src/readiness.ts
index 1423a1a..9bde26b 100644
--- a/node-health/src/readiness.ts
+++ b/node-health/src/readiness.ts
@@ -1,5 +1,5 @@
-/** Return type of a readiness check function */
-export type ReadinessFunctionReturn = {
+/** Readiness check function return type */
+export type ReadinessReturn = {
 	/** Status of the readiness check */
 	status: ReadinessStatus;
 	/** Optional message providing additional information about the readiness check */
@@ -7,45 +7,47 @@ export type ReadinessFunctionReturn = {
 };
 
 /** Function that performs a readiness check */
-export type ReadinessFunction = (check: ReadinessCheck) => Promise<ReadinessFunctionReturn>;
+export type ReadinessCheckFn = (check: ReadinessCheck) => Promise<ReadinessReturn>;
 
-/** Status of a readiness check */
-export type ReadinessStatus = 'ok' | 'error' | 'degraded';
+/** Status of the service readiness */
+export type ReadinessStatus = 'fatal' | 'not_ready' | 'degraded' | 'ready';
 
-const aggregateStatus = (statuses: ReadinessStatus[]): ReadinessStatus => {
-	if (statuses.includes('error')) return 'error';
+/** Returns the worst readiness status from a list of statuses. */
+const worstStatus = (statuses: ReadinessStatus[]): ReadinessStatus => {
+	if (statuses.includes('fatal')) return 'fatal';
+	if (statuses.includes('not_ready')) return 'not_ready';
 	if (statuses.includes('degraded')) return 'degraded';
-	return 'ok';
+	return 'ready';
 };
 
-/** Represents a readiness check with an optional timeout */
+/** Individual readiness check */
 export type ReadinessCheck = {
 	/** Name of the readiness check */
 	name: string;
 	/** Function that performs the readiness check */
-	fn: ReadinessFunction;
+	fn: ReadinessCheckFn;
 	/** Timeout in milliseconds for the readiness check (default: 5000) */
 	timeout?: number;
 };
 
-/** Result of a system readiness check */
-export type ReadinessResult = {
+/** System readiness status */
+export type Readiness = {
 	/**
 	 * Status of the system readiness check, aggregated as the worst status
-	 * among individual checks. 'unknown' is a special case indicating that
-	 * no checks were performed, used by ScheduledReadiness before the first run.
-	 * */
-	status: ReadinessStatus | 'unknown';
+	 * among individual checks. If no checks have been performed yet, the status
+	 * is 'not_ready'.
+	 */
+	status: ReadinessStatus;
 	/** Start time of the system readiness check in milliseconds since the Unix epoch */
 	start: number;
 	/** Duration of the system readiness check in milliseconds */
 	duration: number;
 	/** Details of individual readiness checks */
-	details: ReadinessDetail[];
+	details: ReadinessCheckResult[];
 };
 
-/** Detail of an individual readiness check */
-export type ReadinessDetail = {
+/** System-generated result from an individual readiness check */
+export type ReadinessCheckResult = {
 	/** Name of the readiness check */
 	name: string;
 	/** Status of the readiness check */
@@ -59,12 +61,12 @@ export type ReadinessDetail = {
 /**
  * Performs a readiness check by executing the provided readiness functions.
  * @param checks - An array of readiness functions to execute.
- * @returns A Promise that resolves to a ReadinessResult object.
+ * @returns A Promise that resolves to a Readiness object.
  */
-export const readiness = async (checks: ReadinessCheck[]): Promise<ReadinessResult> => {
+export const readiness = async (checks: ReadinessCheck[]): Promise<Readiness> => {
 	const start = Date.now();
 	const t0 = performance.now();
-	const details: ReadinessDetail[] = [];
+	const details: ReadinessCheckResult[] = [];
 
 	for (const check of checks) {
 		const checkt0 = performance.now();
@@ -83,7 +85,7 @@ export const readiness = async (checks: ReadinessCheck[]): Promise<ReadinessResu
 		} catch (err) {
 			details.push({
 				name: check.name,
-				status: 'error',
+				status: 'fatal',
 				message: err instanceof Error ? err.message : String(err),
 				duration: performance.now() - checkt0,
 			});
@@ -93,7 +95,7 @@ export const readiness = async (checks: ReadinessCheck[]): Promise<ReadinessResu
 	const duration = performance.now() - t0;
 
 	return {
-		status: aggregateStatus(details.map((d) => d.status)),
+		status: worstStatus(details.map((d) => d.status)),
 		start,
 		duration,
 		details,
@@ -104,7 +106,7 @@ export const readiness = async (checks: ReadinessCheck[]): Promise<ReadinessResu
  * Creates a handler function for readiness HTTP requests. Warning: this runs all
  * checks on each request and may be slow.
  * @param checks - An array of readiness functions to execute.
- * @returns A function that returns a Response object with ReadinessResult in JSON format.
+ * @returns A function that returns a Response object with Readiness in JSON format.
  */
 export const createReadinessHandler = (checks: ReadinessCheck[]): (() => Promise<Response>) => {
 	return async () => {
@@ -121,8 +123,8 @@ export class ScheduledReadiness {
 	private interval: number;
 	private started: boolean = false;
 	private timer: NodeJS.Timeout | null = null;
-	private latestResult: ReadinessResult | null = null;
-	private nextResult: Promise<ReadinessResult> | null = null;
+	private latestResult: Readiness | null = null;
+	private nextResult: Promise<Readiness> | null = null;
 
 	/**
 	 * Creates an instance of ScheduledReadiness.
@@ -165,7 +167,7 @@ export class ScheduledReadiness {
 	}
 
 	/** Gets the next readiness result, waiting if a check is in progress */
-	async getNextResult(): Promise<ReadinessResult | null> {
+	async getNextResult(): Promise<Readiness | null> {
 		if (this.nextResult) {
 			return await this.nextResult;
 		}
@@ -173,7 +175,7 @@ export class ScheduledReadiness {
 	}
 
 	/** Gets the latest readiness result without waiting */
-	getResult(): ReadinessResult | null {
+	getResult(): Readiness | null {
 		return this.latestResult;
 	}
 
@@ -192,7 +194,7 @@ export class ScheduledReadiness {
 	/**
 	 * Creates a handler function for readiness HTTP requests using the latest scheduled result.
 	 * Scheduled handler always returns the most recent result, or 'unknown' if no checks have run yet.
-	 * @returns A function that returns a Response object with ReadinessResult in JSON format.
+	 * @returns A function that returns a Response object with Readiness in JSON format.
 	 */
 	createHandler(): () => Promise<Response> {
 		return async () => {
@@ -200,13 +202,13 @@ export class ScheduledReadiness {
 			if (!result) {
 				return new Response(
 					JSON.stringify({
-						status: 'unknown',
+						status: 'not_ready',
 						start: Date.now(),
 						duration: 0,
 						details: [],
-					} as ReadinessResult),
+					} as Readiness),
 					{
-						status: httpStatusFromReadiness('unknown'),
+						status: httpStatusFromReadiness('not_ready'),
 						headers: { 'Content-Type': 'application/json' },
 					},
 				);
@@ -217,8 +219,8 @@ export class ScheduledReadiness {
 	}
 }
 
-/** Returns a Response object with the given ReadinessResult in JSON format */
-const respondWithResult = (result: ReadinessResult) => {
+/** Returns a Response object with the given Readiness in JSON format */
+const respondWithResult = (result: Readiness) => {
 	return new Response(JSON.stringify(result), {
 		status: httpStatusFromReadiness(result.status),
 		headers: { 'Content-Type': 'application/json' },
@@ -226,11 +228,11 @@ const respondWithResult = (result: ReadinessResult) => {
 };
 
 /** Returns the HTTP status code corresponding to a given readiness status */
-const httpStatusFromReadiness = (status: ReadinessStatus | 'unknown'): number => {
-	if (status === 'ok') return 200;
+const httpStatusFromReadiness = (status: ReadinessStatus): number => {
+	if (status === 'ready') return 200;
 	if (status === 'degraded') return 200; // 206 could also be suitable, but let's avoid false alarms
-	if (status === 'error') return 503;
-	return 200; // unknown, treat as ok to avoid false alarms
+	if (status === 'fatal') return 503;
+	return 200; // not_ready, treat as ok to avoid false alarms
 };
 
 const withTimeout = async <T>(