Table 1.

Terminology and their operational definitions

Term	Revised Definition	Role in Parent-Led Organizational Interventions
Loneliness	A subjective negative emotional experience (the core intervention target of parent-led organizations), divided into two dimensions (Buecker et al., [21]): • Social loneliness: A subjective sense of deprivation stemming from the lack of meaningful social connections, networks, and group affiliations (Margelisch et al., [23]) and/or group memberships (targeted by addressing “staying at home” or “lack of interaction”); • Emotional loneliness: A sense of loss or emptiness emerging from missing out on deep emotional connection with others (Landmann & Rohmann, [24]) and intimate relationships (e.g., close family or peer bonds, targeted by fostering companion bonds).	Parent-led organizations’ goal is to alleviate this experience—though they frame it as “integration” to avoid stigma.
Being alone	An objective physical state (no immediate social contact). For example, a child playing alone at home.	Not an intervention target, but a baseline state that parent-led organizations monitor to identify potential loneliness risks.
Staying at home	An objective behavioral pattern (prolonged physical isolation within the home, e.g., a child not leaving home for weeks), often associated with increased loneliness risk.	The trigger for organizational intervention—parent-led organizations design “collective outings” to break this pattern.
Solitude	A subjective neutral/positive state (choosing to be alone, e.g., some autistic children prefer quiet, non-interactive environments).	A boundary for organizational intervention—parent-led organizations should avoid forcing “social interaction” on autistic children who prefer solitude (to prevent exacerbating distress).
Lack of interaction	An objective behavioral indicator (no verbal/nonverbal communication with peers/adults during activities, e.g., a child not responding to peers’ greetings).	A measure of intervention effectiveness—parent-led organizations use this to adjust activities (e.g., switching from large-group hiking to small-group art therapy).