Looking at the code, I can see that `skipUndefinedSources` controls whether properties with `undefined` values from the source object are ignored during merging. You're right that the name could be more positive and clearer.

Here are some better alternatives:

**Positive, clear options:**
- `ignoreUndefined` - Simple and positive
- `omitUndefined` - Clear about what gets left out
- `excludeUndefined` - Similar to omit but more explicit
- `requireDefinedValues` - Emphasizes that only defined values are included

**More descriptive options:**
- `onlyDefinedProperties` - Makes it clear what gets processed
- `definedPropertiesOnly` - Alternative phrasing of above
- `includeDefinedOnly` - Positive framing of what gets included
- `filterUndefined` - Suggests filtering out undefined values

**Property-focused options:**
- `skipUndefinedProps` - Shorter than "Sources" and more accurate
- `ignoreUndefinedProps` - Positive version of skip

My top recommendations would be:
1. **`ignoreUndefined`** - Short, positive, and immediately clear
2. **`onlyDefinedProperties`** - More verbose but very explicit about behavior
3. **`omitUndefined`** - Clear and commonly understood in programming contexts

The current name `skipUndefinedSources` is indeed confusing because:
- "Sources" implies multiple source objects, but it applies to properties within sources
- "Skip" is negative framing
- It's not immediately clear what happens when you "skip" them

What do you think of these alternatives?