just so, this, right, justice
是 centers on affirming correctness: something that is right, just, or exactly so. The demonstrative senses (this, here) are natural extensions of pointing to what is correct or agreed upon.
是 is thought to combine 日 (sun) with 正 (correct) in its older form, suggesting the sun as the standard of correctness. The modern lower part is simplified to 疋.
The sun 日 above a straight, upright shape 疋 suggests the sun shining down on what is right and just. When the sun is overhead, everything is clear and correct.
For ゼ, imagine a judge pointing at the sun and declaring 'Zay!' as a firm affirmation of justice: Zay -> ゼ, and the sun confirms what is right.
certainly; without fail
righteousness; justice; right
correction; revision; redressing; rectifying
by all means; at all costs; absolutely
approval; approbation; endorsement
national policy
company policy
free and unbiased; fair and just; ruling or judging what's right is right and what's wrong is wrong; calling spade a spade
party platform; party principles
form is emptiness; matter is void; all is vanity
complete reversal of values or ways of thinking (over time); What appeared wrong in the past now appears right; realizing and regretting the past errors of one's ways
ten thusnesses (in Tendai)
("like this"; often the opening word of a sutra)
thus I hear (quote from the sutras); these ears have heard
reapportionment (of Diet seats)
practical search for the truth
shop policy
this and that; one thing and another
every day is a good day; enjoy every day
complete reversal of values or ways of thinking