Intrusive, a.
Apt to intrude; characterized by intrusion; entering without right or welcome. Intrusive rocks (Geol.), rocks which have been forced, while in a plastic or melted state, into the cavities or between the cracks or layers of other rocks. The term is sometimes used as equivalent to plutonic rocks. It is then contrasted with effusive or volcanic rocks. -- In*tru"sive*ly, adv. -- In*tru"sive*ness, n.
Shades of meaning
Fernald has no entry of its own for intrusive; he lists it under inquisitive, meddlesome.
Where he writes about it:
The meddlesome person interferes unasked in the affairs of others; the intrusive person thrusts himself uninvited into their company or conversation; the obtrusive person thrusts himself or his opinions conceitedly and undesirably upon their notice; the officious person thrusts his services, unasked and undesired, upon others. — from meddlesome
Obtrusive is oftener applied to words, qualities, actions, etc., than to persons; intrusive is used chiefly of persons, as is officious, tho we speak of officious attentions, intrusive remarks; meddlesome is used indifferently of persons, or of words, qualities, actions, etc. — from meddlesome