single word counterpart to the word 'insidious' when the results are beneficial

I’ve been trying to think of a single word counterpart to the word insidious.

Oxford Dictionaries:
insidious (adjective), Proceeding in a gradual, subtle way, but with very harmful effects.

The meaning I require (to describe the action of yeast say within dough or a must, and by metaphorical extension, small acts of kindness in society) is

Proceeding in a gradual, subtle way, with beneficial effects that eventually make a great difference.

There are related words with no implications of good or evil effect: Thesaurus.com gives synonyms for pervasive including permeating and pervading.

Is there though a single word (not a phrase, proverb … please) with the required meaning?


Well, it's kind of simplistic, but it can't be construed as negative... You could use "blossoming".

If you're talking about a societal trend or social movement, I'm afraid the most recognized term is a phrase: grass-roots. (It usually has positive connotations.) (US)


The term burgeoning can mean

To begin to grow or blossom. American Heritage

However, it often has a connotation of rapid or increasing growth.


Perhaps "nurturing" would be suitable.


I would suggest the word leavening.

Practically, leaven is any substance that, added to dough, causes it to rise and increase in size, ready for baking.

But it has, also, a metaphorical meaning :

a pervasive influence that modifies something or transforms it for the better. "they acted as an intellectual leaven to the warriors who dominated the city"

{ODO}


Accumulative (adj) gradually increasing

Proceeding in a such a way to make accumulative progress and make a great difference

The verb germinate, which by definition is always positive, is normally reserved to biology but it can be employed in a figurative and metaphorical sense too.

Laying/Creating the perfect conditions for [it] to germinate and make a great difference

Cambridge Dictionary defines it as

germinate verb (SEED)

  1. specialized biology to (cause a seed to) start growing:

germinate verb (IDEA)

  1. to start developing: I felt an idea germinating in my head/mind.