diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8795a62f..f62512b7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@
 - Snapshot mismatches show a readable line diff even when `git` is unavailable (expected lines prefixed `-`, actual `+`) (#679)
 - Failure output now includes the originating test `file:line` (`at <file>:<line>`) (#680)
 - Project config file `.bashunitrc` (`KEY=value` lines); precedence is CLI flag > env var / `.env` > `.bashunitrc` > default; honors `--skip-env-file` (#681)
+- Killed tests now report a specific cause instead of a bare "Killed": timeout (124), SIGINT (130), SIGKILL/OOM (137), SIGTERM (143), or "Killed by signal N" (#683)
 
 ### Fixed
 - `bashunit watch` now forwards `--filter` (and other flags) to each run regardless of position, and no longer mangles forwarded arguments (#682)
diff --git a/src/runner.sh b/src/runner.sh
index 7a9b098f..7bc201d5 100755
--- a/src/runner.sh
+++ b/src/runner.sh
@@ -194,6 +194,32 @@ function bashunit::runner::detect_runtime_error() {
   printf ''
 }
 
+##
+# Maps a process exit code to a human-readable description when it indicates the
+# test was killed by a signal (128 + signal) or timed out. Returns an empty
+# string for ordinary exit codes. Bash 3.0+ compatible.
+# Arguments: $1 exit code
+##
+function bashunit::runner::classify_kill_signal() {
+  local code=$1
+
+  case "$code" in
+  124) printf 'Timed out (killed by `timeout`)' ;;
+  130) printf 'Interrupted (SIGINT)' ;;
+  137) printf 'Killed (SIGKILL — out of memory or forced termination)' ;;
+  143) printf 'Terminated (SIGTERM — e.g. a timeout)' ;;
+  *)
+    # Generic "killed by signal N" for other 128+N codes (signals 1..64)
+    case "$code" in
+    '' | *[!0-9]*) return 0 ;;
+    esac
+    if [ "$code" -gt 128 ] && [ "$code" -le 192 ]; then
+      printf 'Killed by signal %s' "$((code - 128))"
+    fi
+    ;;
+  esac
+}
+
 function bashunit::runner::print_verbose_test_summary() {
   local test_file=$1
   local fn_name=$2
@@ -945,6 +971,19 @@ function bashunit::runner::run_test() {
     elif [ -z "$error_message" ] && [ -n "$hook_message" ]; then
       error_message="$hook_message"
     fi
+
+    # When the test was killed by a signal (or timed out), replace an empty or
+    # generic "Killed" message with a specific cause.
+    if [ -z "$hook_failure" ]; then
+      local kill_message
+      kill_message=$(bashunit::runner::classify_kill_signal "$test_exit_code")
+      if [ -n "$kill_message" ]; then
+        case "$error_message" in
+        '' | *[Kk]illed* | *[Tt]erminated*) error_message="$kill_message" ;;
+        esac
+      fi
+    fi
+
     bashunit::console_results::print_error_test "$failure_function" "$error_message" "$runtime_output"
     bashunit::reports::add_test_failed "$test_file" "$failure_label" "$duration" "$total_assertions" "$error_message"
     bashunit::runner::write_failure_result_output "$test_file" "$failure_function" "$error_message" "$runtime_output"
diff --git a/tests/unit/runner_test.sh b/tests/unit/runner_test.sh
index e75f8ed9..b9d7a58a 100644
--- a/tests/unit/runner_test.sh
+++ b/tests/unit/runner_test.sh
@@ -204,3 +204,31 @@ function test_compute_total_assertions_does_not_touch_caller_locals() {
   assert_same "5" "$_BASHUNIT_RUNNER_TOTAL_OUT"
   assert_same "##ASSERTIONS_PASSED=4##ASSERTIONS_FAILED=1" "$test_execution_result"
 }
+
+function test_classify_kill_signal_sigkill_mentions_oom() {
+  local output
+  output="$(bashunit::runner::classify_kill_signal 137)"
+
+  assert_contains "SIGKILL" "$output"
+  assert_contains "memory" "$output"
+}
+
+function test_classify_kill_signal_sigterm() {
+  assert_contains "SIGTERM" "$(bashunit::runner::classify_kill_signal 143)"
+}
+
+function test_classify_kill_signal_timeout() {
+  assert_contains "Timed out" "$(bashunit::runner::classify_kill_signal 124)"
+}
+
+function test_classify_kill_signal_sigint() {
+  assert_contains "SIGINT" "$(bashunit::runner::classify_kill_signal 130)"
+}
+
+function test_classify_kill_signal_generic_signal() {
+  assert_contains "signal 6" "$(bashunit::runner::classify_kill_signal 134)"
+}
+
+function test_classify_kill_signal_empty_for_normal_exit() {
+  assert_empty "$(bashunit::runner::classify_kill_signal 1)"
+}