-oid, -oidal, -oidism, -odic

(Greek: a suffix; like, resembling, similar to, form)

paranoid
1. Resembling, characteristic of, or affected with paranoia.
2. Exhibiting or characterized by extreme and irrational fear or distrust of others: "He had a paranoid suspicion that government agents were listening to his phone calls."
parasitoid
paratyphoid
An acute infectious disease with symptoms and lesions resembling those of typhoid fever, though milder in character; associated with the presence of the paratyphoid organism of which at least three varieties (types A, B, and C) have been described.
peloid
1. Mudlike or similar to mud.
2. A therapeutic mud preparation; such as, that which is used in mud packs or mud baths.
peptoid
petaloid
Like a petal, similar to a petal.
phalloid
phleboid
1. Resembling a vein, venous.
2. Pertaining to or resembling a vein.
3. Containing many veins.
phycoid
phylloid
phytoid
piarachnoid
The two delicate layers of the meninges, the arachnoid mater and pia mater.
picoid
piloid
Resembling hair.
pithecoid

Inter-related cross references, directly or indirectly, involving word units dealing with "form, shape, appearance": eido-; figur-; form-; icono-; ideo-; imag-; morpho-; typo-.