Something that is easy is by definition not hard or difficult. When an activity or goal can be carried out or achieved with little difficulty or effort, it may be called facile. A facile victory, for instance, is a victory won handily with minimal exertion. Similarly, someone who is facile with words expresses themself with ease. While these senses of facile connote skillfulness, facile sometimes sports an air of superficiality: facile answers are overly simplistic or trite responses to difficult questions; facile assumptions are things taken for granted that really shouldn't be; and facile arguments are shallow lines of reasoning—all things formed or arrived at a little too easily.

When we understand something, we perceive the meaning of it. When we fathom something, the perception goes a little deeper. To fathom something is to penetrate to the truth of it, or plumb its depths. The word gets its depth, so to speak, from the noun sense of fathom, a unit of measurement equivalent to six feet used for gauging depth in water. Consequently, one can fathom (measure the depth of) a body of water, or fathom (attempt to get to the bottom of) a difficult or complicated matter. Such depths may seem profound and hard to comprehend, which is perhaps why fathom is so frequently used when full comprehension feels just out of reach.

An idea is a thought or conception, a product of mental activity. A notion is an idea in the most general sense, but the term usually suggests thoughts of more fleeting, vague, or imperfect kind. Whereas an idea can be something fairly worked out or elaborate, perhaps even a plan of action (The student has an idea for how to become an engineer), a notion is more like a whim or impulse—a flurry of thought that hasn't been seriously worked out. Perhaps this half-baked quality explains why notions are so often rejected, challenged, or dismissed! When used in the plural, notions can take on a whole new meaning: small items used in sewing, such as buttons, hooks, and ribbon. 

Items or ideas that are similar have a likeness or resemblance, especially in a general way. The adjective akin suggests a closer affinity or shared nature. The primary meaning of akin is "related by blood," with the root word kin meaning "family relatives collectively" or "a relative." Akin doesn't always imply familial connection, but it does suggest a sameness of character or properties, as what might result from shared ancestry. Akin often shows up sentences that compare one experience, sensation, or feeling to another stronger or more intense feeling, as in "What he felt was akin to love."

Without a doubt, nice is a well-liked adjective. So much so, that it's used almost to the point of cliché! When you are looking for something with a little more heart, try cordial. Cordial means courteous and gracious. It comes from the Latin noun cor meaning "heart." Cordial is commonly used to describe social interactions, as greetings and meetings. While it has cooled off a bit since its earliest uses in English, which emphasized a deeply heartfelt sincerity, it still conveys warmth and friendliness. When used to describe relations of a professional nature, it skews more toward the head than the heart, connoting politeness and civility.

When it comes to attention and what we do with it, the verbs focus and concentrate are very close in meaning. So close, in fact, they are often used interchangeably! Any difference in the terms is slight, but in some uses, concentrate may imply a more involved action. Think of the act of concentrating, which involves close mental application. To concentrate on a problem, then, is to bring all efforts and faculties to bear on it. Both concentrate and focus deal with the idea of bringing things toward a point of convergence; where they notably diverge is in focus's foray into optics (to focus the lens of a camera) and concentrate's dabbling in chemistry (to concentrate a sauce by boiling it down), which gives concentrate an intensifying edge.

To be angry is to experience strong feelings of displeasure. To be indignant is to feel deep anger at something considered unjust or offensive. Indignation is righteous anger, or anger that is morally justified. Someone who is indignant perceives insult or injury to their own or someone else's dignity. The term carries traces of scorn and contempt, and sometimes implies sanctimonious disdain. This range in meaning helps to explain why you might see indignant with a modifier, such as rightly indignant, justly indignant, and genuinely indignant.