batke gismu

x1 is a button/knob/[handle] on/for item x2, with purpose x3, made of material x4.

See also jadni, balji, punji, jgari, lasna.

In notes:

balji
x1 is a bulb [body-part] of plant/species x2; [metaphor: rounded, bulgy].
jadni
x1 (object) adorns/decorates x2; x1 is an adornment/decoration of x2; x2 is fancy/decorated.
jgari
x1 grasps/holds/clutches/seizes/grips/[hugs] x2 with x3 (part of x1) at locus x4 (part of x2).
lasna
x1 (agent) fastens/connects/attaches/binds/lashes x2 to x3 with fastener x4.
punji
x1 (agent) puts/places/sets x2 on/at surface/locus x3.
batkyuidje
b1=u1 is a button in user interface b2=u2 with purpose b3.
gusybatke
b1 is a light switch which is on b2 and made from material b4 and controlling the light source g3.
jadypijne
p1 is a brooch/fibula for fastening to/piercing p2, of material/properties p3.
selbatke
x2=b1 is a button/knob/handle on/for item x1=b2, with purpose x3=b3, made of material x4=b4.
terbatke
x3=b1 is a button/knob/handle on/for item x2=b2, with purpose x1=b3, made of material x4=b4.
velbatke
x4=b1 is a button/knob/handle on/for item x2=b2, with purpose x3=b3, made of material x1=b4.
iklki
x1 clicks (press and release) button/switch x2 to cause x3 (nu).
klikeia
x1 clicks (press and release) button/switch x2
uidje
x1 is a widget of user interface x2.